feat(gateway): integrate OpenClaw as git submodule

- Add OpenClaw as git submodule at ./openclaw/
- Update GatewayManager to start gateway from submodule path
- Support both production (dist) and development (pnpm dev) modes
- Add IPC handler for OpenClaw status check
- Update Setup wizard to check real OpenClaw submodule status
- Configure electron-builder to include submodule in packaged app
- Add npm scripts for submodule management:
  - postinstall: auto-init submodule
  - openclaw:init: initialize and install dependencies
  - openclaw:install: install dependencies only
  - openclaw:build: build OpenClaw
  - openclaw:update: update to latest version

electron/preload/index.ts

@@ -22,6 +22,9 @@ const electronAPI = {
         'gateway:restart',
         'gateway:rpc',
         'gateway:health',
+        // OpenClaw
+        'openclaw:status',
+        'openclaw:isReady',
         // Shell
         'shell:openExternal',
         'shell:showItemInFolder',