fix: check navigator.mediaDevices exists before using getUserMedia

mediaDevices is undefined in non-secure contexts (HTTP). This caused
'Cannot read properties of undefined' errors on web version.

Author: ammar-agent

src/browser/hooks/useVoiceInput.ts

@@ -48,7 +48,10 @@ function hasTouchDictation(): boolean {
 }
 
 const HAS_TOUCH_DICTATION = hasTouchDictation();
-const HAS_MEDIA_RECORDER = typeof window !== "undefined" && typeof MediaRecorder !== "undefined";
+const HAS_MEDIA_RECORDER =
+  typeof window !== "undefined" &&
+  typeof MediaRecorder !== "undefined" &&
+  typeof navigator.mediaDevices?.getUserMedia === "function";
 
 // =============================================================================
 // Hook