fix(deploy): use expose instead of host ports for Coolify compose

Coolify honors host port bindings in the compose and the host already has :80
(its own proxy) and :8000 allocated, so publishing them fails the deploy at
container start. Switch web/api to expose-only; nginx still reaches api over the
compose network, and Coolify routes the domain via docker_compose_domains. Add a
docker-compose.override.yml so local 'docker compose up' still publishes ports.

docker-compose.yml

@@ -1,8 +1,11 @@
 services:
   web:
     build: .
-    ports:
-      - "80:80"
+    # No host port binding: Coolify's proxy routes the domain to this service
+    # over the internal network (see docker_compose_domains). Host bindings
+    # would collide with Coolify's own :80 / other apps on the host.
+    expose:
+      - "80"
     depends_on:
       - api
 
@@ -18,5 +21,7 @@ services:
       - SLACK_BOT_TOKEN=${SLACK_BOT_TOKEN:-}
     volumes:
       - ./data:/app/data
-    ports:
-      - "8000:8000"
+    # Internal only — the web (nginx) service reaches it at http://api:8000 on
+    # the compose network. Not published to the host.
+    expose:
+      - "8000"