feat: add WeChat QR code login and AGP WebSocket channel plugin

- Auth module: WeChat OAuth2 scan-to-login flow with terminal QR code
- Token persistence to ~/.openclaw/wechat-access-auth.json (chmod 600)
- Token resolution: config > saved state > interactive login
- Invite code verification (configurable bypass)
- Production/test environment support
- AGP WebSocket client with heartbeat, reconnect, wake detection
- Message handler: Agent dispatch with streaming text and tool calls
- Random device GUID generation (persisted, no real machine ID)

.gitignore

@@ -0,0 +1,21 @@
+node_modules/
+dist/
+*.js
+*.d.ts
+*.js.map
+*.d.ts.map
+!jest.config.js
+!vitest.config.js
+
+# Auth state (tokens)
+.openclaw/
+
+# OS
+.DS_Store
+Thumbs.db
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo