fix: harden install queue/dispatcher lifecycle and repair review-sweep regressions (#395)

Fixes 15 defects found by a max-effort multi-agent review of the last 6
merged PRs (#388, #390, #391, #392, #393, #394), all adversarially
verified before fixing.

Install queue + dispatcher (the serious cluster):

- features.ts: finalize the installer child exactly once. A failed spawn
  fires both "error" and "close", and the second event released the file
  lock and active slot that pump() had just handed to the next queued
  bundle, letting two pip processes write the same venv concurrently.
  Outcome recording now happens before pump() so the next bundle's first
  progress frame cannot race the previous install's bookkeeping.
- feature-status.ts: keep failed-install errors in a per-bundle map
  instead of the single progress slot. With the queue auto-starting the
  next install, the slot was overwritten within seconds and a failed
  install vanished without ever surfacing to GET /features.
- bridge.ts: scope child lifecycle per process (stopped-children set +
  request generation tags) instead of an instance-wide shuttingDown flag
  that the next spawn reset. A stale SIGTERMed child's late close event
  could record a phantom crash (5 of which permanently disable the
  dispatcher), null out the freshly spawned child, and reject the new
  child's pending requests. The request-timeout kill path still counts
  as a real crash.
- install_feature.py: the pre-write disk re-check measured ai_dir's
  filesystem even when budgeting the cross-filesystem copy that lands on
  the venv's disk; now each budget is checked against the filesystem the
  bytes actually land on, so ENOSPC cannot strike mid-write and leave
  site-packages half overwritten.

Behavior regressions:

- embed-subtitles: preserve pre-existing subtitle tracks (0:s?) and MKV
  attachments (0:t?) that the -map 0:v:0/0:a? rewrite silently dropped;
  data streams stay unmapped on purpose (the actual MPEG remux fix). The
  new subtitle maps first so the language tag hits the right stream.
- usage-survey-overlay: fail closed when the settings fetch fails; the
  fail-open path rendered the blocking survey against an unhealthy API
  and soft-locked admins, the lock-out class #392 fixed.
- features-store: queued bundles poll instead of each holding an SSE
  connection (Install All could pin 7 EventSources and exhaust the
  browser's 6-per-origin HTTP/1.1 limit, hanging the whole app);
  listenToProgress closes any prior stream and stops any poll before
  subscribing; installAll skips bundles already installing or queued.

Contracts, tests, i18n:

- openapi.yaml: add "queued" to the features status enum and document
  downloadBytes/installedBytes (Schemathesis conformance).
- feature-lifecycle e2e: queue transcription (~0.5 GB) instead of ocr
  (~6 GB) and give the test a budget that covers both install drains
  (the stacked waits exceeded the old 900s timeout).
- docker-compose.qa.yml: parameterize the host port (QA_APP_PORT) so
  QA_PROJECT_NAME concurrent stacks can actually bind.
- compare + watermark-image: restore per-input error attribution
  ("Invalid first/second image", "Invalid watermark image") lost in the
  shared-handler migration.
- ai-features-section: the "{size} on disk" suffix now goes through
  i18n; key added to all 21 locales.
- watermark-image + content-aware-resize: migrate to the shared
  inputHandlerFor("image") chain like compare/vectorize/compose, fixing
  drift in the inline copies (no SVG sanitize, no RAW extension hint,
  no AVIF probe).

Verified: typecheck across 9 workspaces, Biome clean on all changed
files, 584 targeted unit tests and 249 integration tests green
(including real-ffmpeg embed-subtitles runs). One unit test updated to
the new poll-while-queued contract with a single-EventSource assertion.

Claude-Session: https://claude.ai/code/session_017mR1HiHaf3a1BmUtrHX4j3

packages/shared/src/i18n/ar.ts

@@ -3475,6 +3475,7 @@ export const ar: TranslationKeys = {
       description: "إدارة حزم نماذج AI لمعالجة الملفات المتقدمة.",
       installAll: "تثبيت الكل",
       diskUsage: "استخدام القرص: {size}",
+      sizeOnDisk: "{size} على القرص",
       installed: "مُثبَّت",
       notInstalled: "غير مُثبَّت",
       queued: "في قائمة الانتظار",

packages/shared/src/i18n/de.ts

@@ -3512,6 +3512,7 @@ export const de: TranslationKeys = {
       description: "AI-Modellpakete für erweiterte Dateiverarbeitung verwalten.",
       installAll: "Alle installieren",
       diskUsage: "Speicherplatznutzung: {size}",
+      sizeOnDisk: "{size} auf der Festplatte",
       installed: "Installiert",
       notInstalled: "Nicht installiert",
       queued: "In Warteschlange",

packages/shared/src/i18n/en.ts

@@ -3425,6 +3425,7 @@ export const en = {
       description: "Manage AI model bundles for advanced file processing.",
       installAll: "Install All",
       diskUsage: "Disk usage: {size}",
+      sizeOnDisk: "{size} on disk",
       installed: "Installed",
       notInstalled: "Not installed",
       queued: "Queued",

packages/shared/src/i18n/es.ts

@@ -3492,6 +3492,7 @@ export const es: TranslationKeys = {
       description: "Gestiona paquetes de modelos AI para procesamiento avanzado de archivos.",
       installAll: "Instalar todo",
       diskUsage: "Uso del disco: {size}",
+      sizeOnDisk: "{size} en disco",
       installed: "Instalado",
       notInstalled: "No instalado",
       queued: "En cola",

packages/shared/src/i18n/fr.ts

@@ -3516,6 +3516,7 @@ export const fr: TranslationKeys = {
       description: "Gérez les paquets de modèles AI pour le traitement avancé de fichiers.",
       installAll: "Tout installer",
       diskUsage: "Utilisation du disque : {size}",
+      sizeOnDisk: "{size} sur le disque",
       installed: "Installé",
       notInstalled: "Non installé",
       queued: "En file d'attente",

packages/shared/src/i18n/hi.ts

@@ -3303,6 +3303,7 @@ export const hi: TranslationKeys = {
       description: "उन्नत फ़ाइल प्रोसेसिंग के लिए AI मॉडल बंडल प्रबंधित करें।",
       installAll: "सभी इंस्टॉल करें",
       diskUsage: "डिस्क उपयोग: {size}",
+      sizeOnDisk: "डिस्क पर {size}",
       installed: "इंस्टॉल किया गया",
       notInstalled: "इंस्टॉल नहीं है",
       queued: "कतार में",

packages/shared/src/i18n/id.ts

@@ -3494,6 +3494,7 @@ export const id: TranslationKeys = {
       description: "Kelola bundel model AI untuk pemrosesan file tingkat lanjut.",
       installAll: "Instal Semua",
       diskUsage: "Penggunaan disk: {size}",
+      sizeOnDisk: "{size} di disk",
       installed: "Terinstal",
       notInstalled: "Belum terinstal",
       queued: "Dalam antrean",

packages/shared/src/i18n/it.ts

@@ -3506,6 +3506,7 @@ export const it: TranslationKeys = {
       description: "Gestisci pacchetti di modelli di IA per l'elaborazione avanzata dei file.",
       installAll: "Installa tutto",
       diskUsage: "Utilizzo del disco: {size}",
+      sizeOnDisk: "{size} su disco",
       installed: "Installato",
       notInstalled: "Non installato",
       queued: "Code",

packages/shared/src/i18n/ja.ts

@@ -3445,6 +3445,7 @@ export const ja: TranslationKeys = {
       description: "高度なファイル処理のためのAIモデルバンドルを管理します。",
       installAll: "すべてインストール",
       diskUsage: "ディスク使用量: {size}",
+      sizeOnDisk: "ディスク上 {size}",
       installed: "インストール済み",
       notInstalled: "未インストール",
       queued: "待機中",

packages/shared/src/i18n/ko.ts

@@ -3429,6 +3429,7 @@ export const ko: TranslationKeys = {
       description: "고급 파일 처리를 위한 AI 모델 번들을 관리합니다.",
       installAll: "모두 설치",
       diskUsage: "디스크 사용량: {size}",
+      sizeOnDisk: "디스크에 {size}",
       installed: "설치됨",
       notInstalled: "설치되지 않음",
       queued: "대기 중",

packages/shared/src/i18n/nl.ts

@@ -3502,6 +3502,7 @@ export const nl: TranslationKeys = {
       description: "Beheer AI-modelbundels voor geavanceerde bestandsverwerking.",
       installAll: "Alles installeren",
       diskUsage: "Schijfgebruik: {size}",
+      sizeOnDisk: "{size} op schijf",
       installed: "Geïnstalleerd",
       notInstalled: "Niet geïnstalleerd",
       queued: "In wachtrij",

packages/shared/src/i18n/pl.ts

@@ -3507,6 +3507,7 @@ export const pl: TranslationKeys = {
       description: "Zarządzanie pakietami modeli AI do zaawansowanego przetwarzania plików.",
       installAll: "Zainstaluj wszystkie",
       diskUsage: "Wykorzystanie dysku: {size}",
+      sizeOnDisk: "{size} na dysku",
       installed: "Zainstalowane",
       notInstalled: "Niezainstalowane",
       queued: "W kolejce",

packages/shared/src/i18n/pt-BR.ts

@@ -3500,6 +3500,7 @@ export const ptBR: TranslationKeys = {
       description: "Gerencie pacotes de modelos de IA para processamento avançado de arquivos.",
       installAll: "Instalar tudo",
       diskUsage: "Uso do disco: {size}",
+      sizeOnDisk: "{size} em disco",
       installed: "Instalado",
       notInstalled: "Não instalado",
       queued: "Na fila",

packages/shared/src/i18n/ru.ts

@@ -3497,6 +3497,7 @@ export const ru: TranslationKeys = {
       description: "Управление пакетами AI-моделей для расширенной обработки файлов.",
       installAll: "Установить все",
       diskUsage: "Использование диска: {size}",
+      sizeOnDisk: "{size} на диске",
       installed: "Установлено",
       notInstalled: "Не установлено",
       queued: "В очереди",

packages/shared/src/i18n/sv.ts

@@ -3492,6 +3492,7 @@ export const sv: TranslationKeys = {
       description: "Hantera AI-modellpaket för avancerad filbehandling.",
       installAll: "Installera alla",
       diskUsage: "Diskanvändning: {size}",
+      sizeOnDisk: "{size} på disk",
       installed: "Installerad",
       notInstalled: "Inte installerad",
       queued: "I kö",

packages/shared/src/i18n/th.ts

@@ -3456,6 +3456,7 @@ export const th: TranslationKeys = {
       description: "จัดการชุดโมเดล AI สำหรับการประมวลผลไฟล์ขั้นสูง",
       installAll: "ติดตั้งทั้งหมด",
       diskUsage: "การใช้พื้นที่ดิสก์: {size}",
+      sizeOnDisk: "{size} บนดิสก์",
       installed: "ติดตั้งแล้ว",
       notInstalled: "ยังไม่ได้ติดตั้ง",
       queued: "อยู่ในคิว",

packages/shared/src/i18n/tr.ts

@@ -3500,6 +3500,7 @@ export const tr: TranslationKeys = {
       description: "Gelişmiş dosya işleme için AI model paketlerini yönetin.",
       installAll: "Tümünü Kur",
       diskUsage: "Disk kullanımı: {size}",
+      sizeOnDisk: "diskte {size}",
       installed: "Kurulu",
       notInstalled: "Kurulu değil",
       queued: "Sırada",

packages/shared/src/i18n/uk.ts

@@ -3497,6 +3497,7 @@ export const uk: TranslationKeys = {
       description: "Керування пакетами AI-моделей для розширеної обробки файлів.",
       installAll: "Встановити все",
       diskUsage: "Використання диска: {size}",
+      sizeOnDisk: "{size} на диску",
       installed: "Встановлено",
       notInstalled: "Не встановлено",
       queued: "У черзі",

packages/shared/src/i18n/vi.ts

@@ -3492,6 +3492,7 @@ export const vi: TranslationKeys = {
       description: "Quản lý các gói mô hình AI cho xử lý tệp nâng cao.",
       installAll: "Cài đặt tất cả",
       diskUsage: "Dung lượng đĩa: {size}",
+      sizeOnDisk: "{size} trên ổ đĩa",
       installed: "Đã cài đặt",
       notInstalled: "Chưa cài đặt",
       queued: "Đang chờ",

packages/shared/src/i18n/zh-CN.ts

@@ -3243,6 +3243,7 @@ export const zhCN: TranslationKeys = {
       description: "管理用于高级文件处理的 AI 模型包。",
       installAll: "全部安装",
       diskUsage: "磁盘使用量：{size}",
+      sizeOnDisk: "占用磁盘 {size}",
       installed: "已安装",
       notInstalled: "未安装",
       queued: "排队中",

packages/shared/src/i18n/zh-TW.ts

@@ -3241,6 +3241,7 @@ export const zhTW: TranslationKeys = {
       description: "管理用於進階檔案處理的AI模型套件。",
       installAll: "全部安裝",
       diskUsage: "磁碟使用量：{size}",
+      sizeOnDisk: "佔用磁碟 {size}",
       installed: "已安裝",
       notInstalled: "未安裝",
       queued: "等待中",