feat(audio): add microphone_enabled + audio_input_device settings (FR-CAP-7)

src-tauri/src/models.rs

@@ -214,9 +214,24 @@ pub struct Settings {
     #[serde(default)]
     pub pst_auto_sync: bool,
     // Audio capture device override (FR-CAP-1). `Device::get_id()` string;
-    // None = system default render device (loopback capture has no mic path).
+    // None = system default render device (loopback / system audio).
     #[serde(default)]
     pub audio_output_device: Option<String>,
+    // Microphone capture (FR-CAP-7): mix the user's own voice into the live
+    // transcript. Local-only, no egress; default ON. Turn off to transcribe just
+    // the system/loopback audio, as WA did before.
+    #[serde(default = "default_true")]
+    pub microphone_enabled: bool,
+    // Microphone device override — `Device::get_id()` string; None = system
+    // default capture device.
+    #[serde(default)]
+    pub audio_input_device: Option<String>,
+}
+
+/// serde default for a `bool` field that should be `true` when absent from an
+/// older `settings.json` (so upgrading users get the microphone, FR-CAP-7).
+fn default_true() -> bool {
+    true
 }
 
 // ---- Sync (ADR-0010) ----