fix(gateway): use GitHub URL for OpenClaw submodule and add token auth

- Change submodule URL from local path to https://github.com/openclaw/openclaw.git
- Checkout stable version v2026.2.3
- Add auto-generated gateway token (clawx-xxx) stored in electron-store
- Pass token via --token argument and OPENCLAW_GATEWAY_TOKEN env var
- Include token in WebSocket URL for authentication
- Add --dev and --allow-unconfigured flags for first-time setup

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "openclaw"]
 	path = openclaw
-	url = /Users/guoyuliang/Project/openclaw
+	url = https://github.com/openclaw/openclaw.git