Remove unnecessary Express server in addon-server.ts - implement single-instance locking

[Nat3z]

The addon-server.ts runs an Express server on port 7654 to enforce single-instance behavior. This should be replaced with Electron's built-in requestSingleInstanceLock and second-instance event.

[nat-openclaw]

▶️ Actions Performed

• Inspect addon-server.ts and main.ts instance bridge code — Mapped Express /internal bridge and main.ts handoff flow
• Remove Express /internal routes from addon-server.ts — Removing Express and /internal routes
• Add requestSingleInstanceLock + second-instance in main.ts
• Remove HTTP bridge helpers and registerInstanceBridgeHandlers usage
• Run application typecheck — typecheck passed
• Commit, push, and open PR — PR refactor: replace Express instance bridge with Electron single-instance lock #167 opened

[nat-openclaw]

Implemented the single-instance switch over to Electron’s requestSingleInstanceLock() / second-instance flow.

Changed:

• removed the Express /internal/* bridge from addon-server.ts
• kept the addon WebSocket server on 7654
• moved the focus / game-launch handoff into the primary Electron instance
• dropped the unused express deps

Checks:

• bun run typecheck ✅

PR is up at #167.