MAESTRO: Implement SSE observation feed consumer with channel routing and exponential backoff

Replaces stub start/stop methods with working SSE consumer that connects to
claude-mem worker's /stream endpoint, parses new_observation events, and
forwards formatted messages to configured OpenClaw channels (Telegram, Discord,
Signal, Slack, WhatsApp, Line). Includes reconnection with exponential backoff
(1s-30s), connection state tracking, and on/off command toggle. Added 17 tests
covering unit and SSE integration scenarios.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

openclaw/package.json

@@ -5,9 +5,11 @@
   "type": "module",
   "main": "dist/index.js",
   "scripts": {
-    "build": "tsc"
+    "build": "tsc",
+    "test": "tsc && node --test dist/index.test.js"
   },
   "devDependencies": {
+    "@types/node": "^25.2.1",
     "typescript": "^5.3.0"
   }
 }