feat(rustdesk): 优化视频编码协商和添加公共服务器支持

- 调整视频编码优先级为 H264 > H265 > VP8 > VP9，优先使用硬件编码
- 对接 RustDesk 客户端质量预设 (Low/Balanced/Best) 到 BitratePreset
- 添加 secrets.toml 编译时读取机制，支持配置公共服务器
- 默认公共服务器: rustdesk.mofeng.run:21116
- 前端 ID 服务器输入框添加问号提示，显示公共服务器信息
- 用户留空时自动使用公共服务器

web/src/i18n/en-US.ts

@@ -109,7 +109,13 @@ export default {
     selectFormat: 'Select format...',
     selectResolution: 'Select resolution...',
     selectFps: 'Select FPS...',
-    bitrate: 'Bitrate',
+    bitratePreset: 'Bitrate',
+    bitrateSpeed: 'Speed',
+    bitrateSpeedDesc: '1 Mbps - Lowest latency',
+    bitrateBalanced: 'Balanced',
+    bitrateBalancedDesc: '4 Mbps - Recommended',
+    bitrateQuality: 'Quality',
+    bitrateQualityDesc: '8 Mbps - Best visual',
     browserUnsupported: 'Browser unsupported',
     encoder: 'Encoder',
     changeEncoderBackend: 'Change encoder backend...',
@@ -649,10 +655,14 @@ export default {
       serverSettings: 'Server Settings',
       rendezvousServer: 'ID Server',
       rendezvousServerPlaceholder: 'hbbs.example.com:21116',
-      rendezvousServerHint: 'RustDesk ID server address (required)',
+      rendezvousServerHint: 'Leave empty to use public server',
       relayServer: 'Relay Server',
       relayServerPlaceholder: 'hbbr.example.com:21117',
       relayServerHint: 'Relay server address, auto-derived from ID server if empty',
+      publicServerInfo: 'Public Server Info',
+      publicServerAddress: 'Server Address',
+      publicServerKey: 'Connection Key',
+      usingPublicServer: 'Using public server',
       deviceInfo: 'Device Info',
       deviceId: 'Device ID',
       deviceIdHint: 'Use this ID in RustDesk client to connect',
@@ -721,7 +731,7 @@ export default {
     // Video related
     mjpegMode: 'MJPEG mode has best compatibility, works with all browsers, but higher latency',
     webrtcMode: 'WebRTC mode has lower latency, but requires browser codec support',
-    videoBitrate: 'Higher bitrate means better quality but requires more bandwidth. Adjust based on network',
+    videoBitratePreset: 'Speed: lowest latency, best for slow networks. Balanced: good quality and latency. Quality: best visual, needs good bandwidth',
     encoderBackend: 'Hardware encoder has better performance and lower power. Software encoder has better compatibility',
     // HID related
     absoluteMode: 'Absolute mode maps mouse coordinates directly, suitable for most scenarios',