refactor: Separate git watcher from terminal service

- Create dedicated git-watcher.ts with its own WebSocket server (port 4105)
- Remove git watcher code from terminal.ts (no more PTY dependency)
- Add /ws/git endpoint for Traefik routing
- GitPage now connects to dedicated git WebSocket instead of terminal

server/config.ts

@@ -1,6 +1,7 @@
 // Server configuration
 export const PORT_HTTP = 4101
 export const PORT_TERMINAL = 4103
+export const PORT_GIT = 4105
 
 // Terminal configuration
 export const WORKING_DIR = process.cwd().replace(/[\\\/]server$/, '')