fix: release QA hardening across processing, media, security, and CI gates (#649)

A release-readiness QA pass over the whole product. The commits split into
defects a user would hit and gates that were reporting green while measuring
nothing.

## Fixes that change behaviour

Rate limiting was bypassable on every install: TRUST_PROXY defaulted to true, so
request.ip came from a client-set header and a forged X-Forwarded-For got past
the login limiter. The default is now a private-network trust list.

A transient Postgres outage stranded in-flight jobs, leaving finished output on
disk with no row pointing at it. A reconciler now resolves those rows and adopts
the bytes rather than dropping the work.

A Redis connection that moved to a new address wedged every read-blocked
consumer, so completions stopped signalling while health still answered 200.
Socket timeouts plus subscriber pings recover it.

Installing more than one AI bundle left the shared venv multi-versioned and
silently broke three tools. The installer now reconciles distributions to one
version each.

Converting an image to JXL at quality 1 through 4 returned a 500, because
libjxl 0.7 rejects the distance those values compute. The quality is floored at
what the encoder honours. A missing ffmpeg was also reported to the user as a
corrupt upload; it now says the engine is unavailable.

RAW uploads reached an unpatched LibRaw on arm64, so it is built from source at
0.22.2, and the release scan was split so it can fail on an unfixed critical
instead of hiding it behind ignore-unfixed.

## Gates that could not fail

Two mutation lanes ran zero mutants because Stryker crawled the gitignored docs
build; coverage discarded its whole report on any failing test; the lint gate
skipped root tests, scripts, and two workspaces; and several generated matrices
counted a host missing ffmpeg as a passing tool. Each now measures what it
claims.

Full evidence and the outstanding release items are tracked locally and are not
part of this branch.

apps/docs/zh-TW/guide/architecture.md

@@ -1,8 +1,9 @@
 ---
 description: "SnapOtter 的 monorepo 結構、app 與套件架構、請求生命週期，以及資源占用。"
-i18n_output_hash: 733f35af8cb1
-i18n_source_hash: a53946e760b0
+i18n_source_hash: 50e076925c4b
 i18n_provenance: human
+i18n_output_hash: 712a7e7cf078
+i18n_hash_version: 2
 ---
 
 # 架構 {#architecture}
@@ -52,7 +53,7 @@ Python 腳本位於 `packages/ai/python/` 中。大型可選模型包根據需
 
 ### API（`apps/api`） {#api-apps-api}
 
-一個 Fastify v5 伺服器，公開橫跨五種模態（image、video、audio、PDF、file）的 241 個工具路由，負責處理：
+一個 Fastify v5 伺服器，公開橫跨五種模態（image、video、audio、PDF、file）的 243 個工具路由，負責處理：
 - 檔案上傳、暫存工作區管理，以及持久化檔案儲存
 - 使用者檔案資料庫（`user_files` 資料表）：預設情況下，已儲存的編輯會儲存為一個獨立的新檔案；而當你覆寫原始檔案時，則儲存為一個與父檔案連結的版本。它會記錄套用了哪些工具（`toolChain`），並為 Files 頁面自動產生縮圖
 - 工具執行（將每個工具請求路由至影像引擎或 AI 橋接層）