fix(audio): expose sample rate setting in Convert Audio (#561)

The Convert Audio tool promised configurable bitrate, sample rate, and channel count, but only format and bitrate were exposed. Adds an optional sampleRate setting (8000 to 96000 Hz, omitted = preserve source) wired through the Zod schema, the FFmpeg -ar flag, the standalone settings panel, and the pipeline builder controls.

Impossible combinations fail loudly instead of degrading silently: MP3 + 96000 Hz is rejected (libmp3lame caps at 48 kHz), and MP3 bitrates above the encoder ceiling at low rates (64 kbps at 8 kHz, 160 kbps at 16/22.05 kHz) are rejected rather than clamped. The UI offers only legal combinations and sanitizes stored pipeline settings on load.

Docs updated in English plus all 20 localized pages with refreshed i18n_source_hash stamps; two new UI strings added to all 21 locales.

Fixes #558

packages/shared/src/i18n/ar.ts

@@ -2489,6 +2489,8 @@ export const ar: TranslationKeys = {
     "convert-audio": {
       format: "تنسيق الإخراج",
       bitrate: "معدل البت (kbps)",
+      sampleRate: "معدل أخذ العينات (Hz)",
+      sampleRatePreserve: "الاحتفاظ بالأصلي",
       submit: "تحويل",
       submitBatch: "تحويل ({count} ملفات)",
       progressLabel: "جارٍ التحويل",

packages/shared/src/i18n/de.ts

@@ -2512,6 +2512,8 @@ export const de: TranslationKeys = {
     "convert-audio": {
       format: "Ausgabeformat",
       bitrate: "Bitrate (kbps)",
+      sampleRate: "Abtastrate (Hz)",
+      sampleRatePreserve: "Original beibehalten",
       submit: "Konvertieren",
       submitBatch: "Konvertieren ({count} Dateien)",
       progressLabel: "Wird konvertiert",

packages/shared/src/i18n/en.ts

@@ -2453,6 +2453,8 @@ export const en = {
     "convert-audio": {
       format: "Output format",
       bitrate: "Bitrate (kbps)",
+      sampleRate: "Sample rate (Hz)",
+      sampleRatePreserve: "Preserve original",
       submit: "Convert",
       submitBatch: "Convert ({count} files)",
       progressLabel: "Converting",

packages/shared/src/i18n/es.ts

@@ -2493,6 +2493,8 @@ export const es: TranslationKeys = {
     "convert-audio": {
       format: "Formato de salida",
       bitrate: "Tasa de bits (kbps)",
+      sampleRate: "Frecuencia de muestreo (Hz)",
+      sampleRatePreserve: "Mantener original",
       submit: "Convertir",
       submitBatch: "Convertir ({count} archivos)",
       progressLabel: "Convirtiendo",

packages/shared/src/i18n/fr.ts

@@ -2519,6 +2519,8 @@ export const fr: TranslationKeys = {
     "convert-audio": {
       format: "Format de sortie",
       bitrate: "Débit (kbps)",
+      sampleRate: "Fréquence d'échantillonnage (Hz)",
+      sampleRatePreserve: "Conserver l'originale",
       submit: "Convertir",
       submitBatch: "Convertir ({count} fichiers)",
       progressLabel: "Conversion",

packages/shared/src/i18n/hi.ts

@@ -2319,6 +2319,8 @@ export const hi: TranslationKeys = {
     "convert-audio": {
       format: "आउटपुट फ़ॉर्मैट",
       bitrate: "बिटरेट (kbps)",
+      sampleRate: "सैंपल रेट (Hz)",
+      sampleRatePreserve: "मूल बनाए रखें",
       submit: "कन्वर्ट करें",
       submitBatch: "कन्वर्ट करें ({count} फ़ाइलें)",
       progressLabel: "कन्वर्ट हो रहा है",

packages/shared/src/i18n/id.ts

@@ -2502,6 +2502,8 @@ export const id: TranslationKeys = {
     "convert-audio": {
       format: "Format keluaran",
       bitrate: "Bitrate (kbps)",
+      sampleRate: "Laju sampel (Hz)",
+      sampleRatePreserve: "Pertahankan asli",
       submit: "Konversi",
       submitBatch: "Konversi ({count} file)",
       progressLabel: "Mengonversi",

packages/shared/src/i18n/it.ts

@@ -2507,6 +2507,8 @@ export const it: TranslationKeys = {
     "convert-audio": {
       format: "Formato di output",
       bitrate: "Bitrate (kbps)",
+      sampleRate: "Frequenza di campionamento (Hz)",
+      sampleRatePreserve: "Mantieni originale",
       submit: "Converti",
       submitBatch: "Converti ({count} file)",
       progressLabel: "Conversione",

packages/shared/src/i18n/ja.ts

@@ -2462,6 +2462,8 @@ export const ja: TranslationKeys = {
     "convert-audio": {
       format: "出力形式",
       bitrate: "ビットレート (kbps)",
+      sampleRate: "サンプルレート (Hz)",
+      sampleRatePreserve: "元のまま維持",
       submit: "変換",
       submitBatch: "変換 ({count} ファイル)",
       progressLabel: "変換中",

packages/shared/src/i18n/ko.ts

@@ -2442,6 +2442,8 @@ export const ko: TranslationKeys = {
     "convert-audio": {
       format: "출력 형식",
       bitrate: "비트레이트 (kbps)",
+      sampleRate: "샘플 레이트 (Hz)",
+      sampleRatePreserve: "원본 유지",
       submit: "변환",
       submitBatch: "변환 ({count}개 파일)",
       progressLabel: "변환 중",

packages/shared/src/i18n/nl.ts

@@ -2508,6 +2508,8 @@ export const nl: TranslationKeys = {
     "convert-audio": {
       format: "Uitvoerformaat",
       bitrate: "Bitrate (kbps)",
+      sampleRate: "Samplefrequentie (Hz)",
+      sampleRatePreserve: "Origineel behouden",
       submit: "Converteren",
       submitBatch: "Converteren ({count} bestanden)",
       progressLabel: "Converteren",

packages/shared/src/i18n/pl.ts

@@ -2506,6 +2506,8 @@ export const pl: TranslationKeys = {
     "convert-audio": {
       format: "Format wyjściowy",
       bitrate: "Przepływność (kbps)",
+      sampleRate: "Częstotliwość próbkowania (Hz)",
+      sampleRatePreserve: "Zachowaj oryginalną",
       submit: "Konwertuj",
       submitBatch: "Konwertuj ({count} plików)",
       progressLabel: "Konwertowanie",

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

@@ -2504,6 +2504,8 @@ export const ptBR: TranslationKeys = {
     "convert-audio": {
       format: "Formato de saída",
       bitrate: "Taxa de bits (kbps)",
+      sampleRate: "Taxa de amostragem (Hz)",
+      sampleRatePreserve: "Manter original",
       submit: "Converter",
       submitBatch: "Converter ({count} arquivos)",
       progressLabel: "Convertendo",

packages/shared/src/i18n/ru.ts

@@ -2504,6 +2504,8 @@ export const ru: TranslationKeys = {
     "convert-audio": {
       format: "Формат вывода",
       bitrate: "Битрейт (kbps)",
+      sampleRate: "Частота дискретизации (Hz)",
+      sampleRatePreserve: "Сохранить исходную",
       submit: "Конвертировать",
       submitBatch: "Конвертировать ({count} файлов)",
       progressLabel: "Конвертация",

packages/shared/src/i18n/sv.ts

@@ -2501,6 +2501,8 @@ export const sv: TranslationKeys = {
     "convert-audio": {
       format: "Utdataformat",
       bitrate: "Bithastighet (kbps)",
+      sampleRate: "Samplingsfrekvens (Hz)",
+      sampleRatePreserve: "Behåll original",
       submit: "Konvertera",
       submitBatch: "Konvertera ({count} filer)",
       progressLabel: "Konverterar",

packages/shared/src/i18n/th.ts

@@ -2473,6 +2473,8 @@ export const th: TranslationKeys = {
     "convert-audio": {
       format: "รูปแบบเอาต์พุต",
       bitrate: "บิตเรต (kbps)",
+      sampleRate: "อัตราสุ่มตัวอย่าง (Hz)",
+      sampleRatePreserve: "คงค่าเดิม",
       submit: "แปลง",
       submitBatch: "แปลง ({count} ไฟล์)",
       progressLabel: "กำลังแปลง",

packages/shared/src/i18n/tr.ts

@@ -2506,6 +2506,8 @@ export const tr: TranslationKeys = {
     "convert-audio": {
       format: "Çıktı formatı",
       bitrate: "Bit hızı (kbps)",
+      sampleRate: "Örnekleme hızı (Hz)",
+      sampleRatePreserve: "Orijinali koru",
       submit: "Dönüştür",
       submitBatch: "Dönüştür ({count} dosya)",
       progressLabel: "Dönüştürülüyor",

packages/shared/src/i18n/uk.ts

@@ -2504,6 +2504,8 @@ export const uk: TranslationKeys = {
     "convert-audio": {
       format: "Вихідний формат",
       bitrate: "Бітрейт (kbps)",
+      sampleRate: "Частота дискретизації (Hz)",
+      sampleRatePreserve: "Зберегти вихідну",
       submit: "Конвертувати",
       submitBatch: "Конвертувати ({count} файлів)",
       progressLabel: "Конвертація",

packages/shared/src/i18n/vi.ts

@@ -2503,6 +2503,8 @@ export const vi: TranslationKeys = {
     "convert-audio": {
       format: "Định dạng đầu ra",
       bitrate: "Tốc độ bit (kbps)",
+      sampleRate: "Tần số lấy mẫu (Hz)",
+      sampleRatePreserve: "Giữ nguyên gốc",
       submit: "Chuyển đổi",
       submitBatch: "Chuyển đổi ({count} tệp)",
       progressLabel: "Đang chuyển đổi",

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

@@ -2261,6 +2261,8 @@ export const zhCN: TranslationKeys = {
     "convert-audio": {
       format: "输出格式",
       bitrate: "比特率 (kbps)",
+      sampleRate: "采样率 (Hz)",
+      sampleRatePreserve: "保留原始",
       submit: "转换",
       submitBatch: "转换（{count} 个文件）",
       progressLabel: "正在转换",

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

@@ -2261,6 +2261,8 @@ export const zhTW: TranslationKeys = {
     "convert-audio": {
       format: "輸出格式",
       bitrate: "位元率 (kbps)",
+      sampleRate: "取樣率 (Hz)",
+      sampleRatePreserve: "保留原始",
       submit: "轉換",
       submitBatch: "轉換（{count} 個檔案）",
       progressLabel: "正在轉換",