Remove webhook_receiver host port binding (Coolify proxy handles routing)

Port 8000 was already allocated on the host. On Coolify, Traefik routes
external traffic to the container internally — no host port needed.

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

docker-compose.yaml

@@ -46,8 +46,8 @@ services:
       timescale_db:
         condition: service_healthy
     env_file: .env
-    ports:
-      - "8000:8000"
+    # No host port binding — Coolify's Traefik proxy routes traffic internally.
+    # Set the webhook domain in Coolify UI pointing to this service on port 8000.
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:8000/health"]
       interval: 30s