feat: add HTTP API for E2EE Matrix notifications

- POST /notify: send encrypted message to any room
- GET /messages: read decrypted messages from any room
- GET /health: health check
- Authenticated via BOT_API_KEY header
- Port 9100 exposed in docker-compose

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -27,6 +27,8 @@ services:
       - BOT_API_KEY
       - SKYVERN_BASE_URL=http://skyvern:8000
       - SKYVERN_API_KEY
+    ports:
+      - "9100:9100"
     volumes:
       - bot-data:/data
       # Mount source files so git pull + restart works without rebuild