feat(ui): load language catalog + setWhisperLanguage in settings store (T8.7, M4.2)

src/lib/stores/settings.svelte.ts

@@ -14,6 +14,7 @@ import {
   type HardwareStatus,
   type LlmStatus,
   type ModelInfo,
+  type LanguageOption,
   type PrivacySelfCheck,
   type McpStatus,
   type McpAccessEntry,
@@ -27,6 +28,7 @@ const DEFAULT_SETTINGS: AppSettings = {
   llm_model: "llama3",
   preferred_backend: "auto",
   whisper_model: "base.en-q5_1",
+  whisper_language: null, // auto-detect by default (T8.7, FR-TRX-4)
   low_overhead: false,
   default_record: false, // recording OFF by default (ADR-0009)
   consent_acknowledged: false,
@@ -58,6 +60,8 @@ class SettingsStore {
   // Hardware + model management (Phase 3, T3.6/T3.7).
   hardware = $state<HardwareStatus | null>(null);
   models = $state<ModelInfo[]>([]);
+  // Transcription language catalog for the Settings dropdown (T8.7, FR-TRX-4).
+  languages = $state<LanguageOption[]>([]);
   audioDevices = $state<AudioDeviceInfo[]>([]);
   inputDevices = $state<AudioDeviceInfo[]>([]);
   downloadProgress = $state<Record<string, { received: number; total: number | null }>>({});
@@ -96,6 +100,7 @@ class SettingsStore {
     await this.loadAudioDevices();
     await this.loadInputDevices();
     await this.loadModels();
+    await this.loadLanguages();
     await this.loadPrivacy();
     await this.loadLlmStatus();
     await this.loadMcpStatus();
@@ -193,6 +198,21 @@ class SettingsStore {
     }
   }
 
+  async loadLanguages() {
+    try {
+      this.languages = await api.listWhisperLanguages();
+    } catch {
+      this.languages = [];
+    }
+  }
+
+  /** `null` = auto-detect (T8.7, FR-TRX-4). Only meaningful when the active
+   * model is multilingual — the Settings UI disables/hides this control
+   * otherwise, and the backend forces "en" regardless if it's set anyway. */
+  async setWhisperLanguage(code: string | null) {
+    await this.patch({ whisper_language: code });
+  }
+
   async loadPrivacy() {
     try {
       this.privacy = await api.privacySelfCheck();