feat(mcp): sync MCP servers across enabled CLIs

Adds capabilities.mcpConfig to the CLI registry (Claude, Gemini, Codex,
OpenCode), an additive src/mcp-sync.ts, GET/POST /api/mcp-sync and a
Settings > Agents & CLIs control. Never edits or removes an existing
server; backs up each file it changes; reports conflicts.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/web/server.ts

@@ -197,6 +197,7 @@ import {
   registerVoiceRoutes,
   registerWebviewRoutes,
   registerTabLayoutRoutes,
+  registerMcpSyncRoutes,
   registerCustomModelRoutes,
   refreshAllCustomModelHosts,
   readCustomModelEndpointsEnabled,
@@ -1130,6 +1131,7 @@ export class WebServer extends EventEmitter {
     registerOrchestratorRoutes(this.app, ctx);
     registerWebviewRoutes(this.app, ctx, this.basePath);
     registerTabLayoutRoutes(this.app, ctx);
+    registerMcpSyncRoutes(this.app);
     registerCustomModelRoutes(this.app);
     registerCliRegistryRoutes(this.app);