feat: add Control UI PWA web push support (#44590)

Adds browser PWA manifest and service worker support for the Control UI, plus gateway RPC methods and persisted Web Push subscription handling.

Maintainer verification:
- OPENCLAW_VITEST_MAX_WORKERS=1 pnpm test src/infra/push-web.test.ts src/gateway/server-methods/push.test.ts src/gateway/control-ui.test.ts src/gateway/protocol/push.test.ts
- pnpm check:changed passed before final GitHub update-branch merge commit
- pnpm build

Source head: 0720024368

package.json

@@ -1642,6 +1642,7 @@
     "tslog": "^4.10.2",
     "typebox": "1.1.31",
     "undici": "8.1.0",
+    "web-push": "^3.6.7",
     "ws": "^8.20.0",
     "yaml": "^2.8.3",
     "zod": "^4.3.6"