Use expose instead of ports for Coolify deployment

Coolify handles reverse proxying internally, so binding to a host port
is unnecessary and causes conflicts. expose makes port 8000 available
within the Docker network without publishing it to the host.

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

docker-compose.yaml

@@ -2,8 +2,8 @@ services:
   web:
     build: .
     container_name: cot_web
-    ports:
-      - "8000:8000"
+    expose:
+      - "8000"
     volumes:
       - cot_data:/data
     environment: