feat(tauri): 摄像头/麦克风权限配置（macOS 授权一次 + Windows 兼容）

- Info.plist：NSCameraUsageDescription / NSMicrophoneUsageDescription（授权一次后不再询问）
- tauri.conf.json：macOSPrivateApi + WebView2 autoplay 允许（自动问候语音不被拦）+ nsis/app/dmg 双平台打包
- Cargo.toml：tauri 启用 macos-private-api feature

src-tauri/tauri.conf.json

@@ -10,12 +10,14 @@
     "frontendDist": "../dist"
   },
   "app": {
+    "macOSPrivateApi": true,
     "windows": [
       {
         "title": "昆明大学生创业园展播系统",
         "width": 1200,
         "height": 800,
-        "fullscreen": true
+        "fullscreen": true,
+        "additionalBrowserArgs": "--autoplay-policy=no-user-gesture-required --enable-features=WebRtcHideLocalIpsWithMdns"
       }
     ],
     "security": {
@@ -24,7 +26,10 @@
   },
   "bundle": {
     "active": true,
-    "targets": ["nsis"],
+    "targets": ["nsis", "app", "dmg"],
+    "macOS": {
+      "minimumSystemVersion": "10.15"
+    },
     "icon": [
       "icons/32x32.png",
       "icons/128x128.png",