agent: fix — auto-grant microphone permission on WebKitGTK/Linux

WebKitGTK denies getUserMedia by default with no permission prompt.
Connect to the permission-request signal and auto-allow, plus enable
media-stream and media-capabilities in WebKit settings.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/lib.rs

@@ -94,6 +94,34 @@ pub fn run() {
                     let _ = main_window.eval(&init_script);
                 }
 
+                // Auto-grant microphone permission on Linux (WebKitGTK).
+                // WebKitGTK doesn't show a permission dialog — it just denies
+                // getUserMedia by default. We connect to the permission-request
+                // signal and grant audio capture requests automatically.
+                #[cfg(target_os = "linux")]
+                {
+                    main_window.with_webview(|webview| {
+                        use webkit2gtk::{
+                            PermissionRequest, PermissionRequestExt,
+                            SettingsExt, WebViewExt,
+                        };
+
+                        let wv: webkit2gtk::WebView = webview.inner().clone();
+
+                        // Enable media stream in WebKit settings
+                        if let Some(settings) = WebViewExt::settings(&wv) {
+                            settings.set_enable_media_stream(true);
+                            settings.set_enable_media_capabilities(true);
+                        }
+
+                        // Auto-grant all permission requests (audio/video capture)
+                        WebViewExt::connect_permission_request(&wv, |_wv, request: &PermissionRequest| {
+                            request.allow();
+                            true
+                        });
+                    }).expect("Failed to configure webview media permissions");
+                }
+
                 // Close-to-tray: hide window instead of exiting
                 let win = main_window.clone();
                 main_window.on_window_event(move |event| {