feat(transcription): add multilingual/language fields to ModelInfo+Settings (T8.7, M4.2)

src-tauri/src/models.rs

@@ -45,6 +45,19 @@ pub struct ModelInfo {
     pub size_mb: u32, // approximate download size
     pub installed: bool,
     pub active: bool,
+    /// `false` for the `.en` (English-only) ggml variants; `true` for the
+    /// multilingual variants (no `.en` suffix, T8.7/FR-TRX-4/M4.2) — gates
+    /// whether the Settings language picker is enabled for this model.
+    pub multilingual: bool,
+}
+
+/// One selectable transcription language (T8.7, FR-TRX-4) — ISO-639-1 code
+/// (as accepted by `whisper_rs::FullParams::set_language`) plus a display
+/// label for the Settings dropdown.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct LanguageOption {
+    pub code: String,
+    pub label: String,
 }
 
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
@@ -198,6 +211,15 @@ pub struct Settings {
     pub llm_advanced: serde_json::Value,
     pub preferred_backend: String, // auto|npu|nvidia|amd|intel|cpu
     pub whisper_model: String,     // ModelInfo.id, e.g. "base.en-q5_1"
+    /// Global default transcription language (T8.7, FR-TRX-4): `None`/`"auto"`
+    /// lets whisper.cpp auto-detect; an ISO-639-1 code (e.g. "es") forces
+    /// that language. Only takes effect with a multilingual model loaded —
+    /// an English-only (`.en`) model always decodes English regardless of
+    /// this setting (see `transcription::resolve_language`). Each meeting
+    /// persists whatever was actually used at `Meeting.language`, so this is
+    /// just the default applied at the next `start_recording`.
+    #[serde(default)]
+    pub whisper_language: Option<String>,
     pub low_overhead: bool,
     // Recording retention (ADR-0009). Default OFF.
     pub default_record: bool,