fix(desktop): 麦克风优雅降级 + Info.plist 加 NSMicrophoneUsageDescription

- voice.ts: startMic 前探测 navigator.mediaDevices?.getUserMedia——WKWebView(原生壳)非安全
  上下文里它可能未暴露,直接调会抛 "undefined is not an object" 崩掉;改为给可读提示
- build/darwin/Info.plist + Info.dev.plist: 加 NSMicrophoneUsageDescription,否则 macOS
  不会授权麦克风(package 后的 .app 才能弹权限)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

sundynix-desktop/build/darwin/Info.dev.plist

@@ -27,6 +27,8 @@
 			<key>NSAllowsLocalNetworking</key>
 			<true/>
 		</dict>
+		<key>NSMicrophoneUsageDescription</key>
+		<string>JARVIS 语音助手需要麦克风来听你说话。</string>
 		<key>NSHighResolutionCapable</key>
 		<string>true</string>
 		<key>NSHumanReadableCopyright</key>

sundynix-desktop/build/darwin/Info.plist

@@ -22,6 +22,8 @@
 		<string>0.1.1</string>
 		<key>LSMinimumSystemVersion</key>
 		<string>12.0.0</string>
+		<key>NSMicrophoneUsageDescription</key>
+		<string>JARVIS 语音助手需要麦克风来听你说话。</string>
 		<key>NSHighResolutionCapable</key>
 		<string>true</string>
 		<key>NSHumanReadableCopyright</key>

sundynix-desktop/frontend/src/lib/voice.ts

@@ -196,6 +196,11 @@ export class VoiceClient {
 
   private async startMic(): Promise<void> {
     if (this.micNode) return;
+    // WKWebView（Wails 原生壳）等非安全上下文里 navigator.mediaDevices 可能未暴露——
+    // 直接调用会抛 "undefined is not an object" 崩掉。先探测，给出可读提示而非崩溃。
+    if (!navigator.mediaDevices?.getUserMedia) {
+      throw new Error("此窗口暂不支持麦克风（原生壳需授权/安全上下文）。用浏览器打开 localhost:5173 可直接说话。");
+    }
     const stream = await navigator.mediaDevices.getUserMedia({
       audio: { channelCount: 1, echoCancellation: true, noiseSuppression: true },
     });