feat: media send/receive (intent-based + notification bridge)

- POST /messages/send-media: multipart upload + adb push + intent + Appium
- Webhook mediaType: image detection + adb pull + fanout met download-url
- Download endpoint /download/:token (10 min TTL, cleanup every 5 min)
- Android NotificationListener: detecteert media-notificaties (lege/emoji text)
- Dockerfile: adb toegevoegd voor push/pull
- MEDIA_WAIT_MS env var (default 8000ms) voor pull-timing

docker-compose.yml

@@ -23,4 +23,5 @@ services:
       - APPIUM_PORT=4723
       - PORT=3010
       - WEBHOOK_SHARED_SECRET=${WEBHOOK_SHARED_SECRET:-dev-secret-change-me}
+      - MEDIA_WAIT_MS=${MEDIA_WAIT_MS:-8000}
     restart: unless-stopped