chore: adapt Dockerfile/compose for standalone server repo

- Dockerfile no longer bakes in a Flutter web build (this repo has no
  client/ dir); the web bundle is mounted at runtime instead.
- docker-compose.yml: web bundle mount path configurable via
  WEB_CLIENT_BUILD_PATH, defaults to a sibling KC-APP checkout.
- README: point to the KC-APP client repo for clients.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker-compose.yml

@@ -22,21 +22,27 @@ services:
     depends_on:
       db:
         condition: service_healthy
-    # All non-DB config comes from backend/.env (needs Docker Compose v2,
-    # which strips surrounding quotes). DATABASE_URL and the FCM credential
-    # path are overridden below for the container.
+    # All non-DB config comes from .env (needs Docker Compose v2, which
+    # strips surrounding quotes). DATABASE_URL and the FCM credential path
+    # are overridden below for the container.
     env_file:
-      - backend/.env
+      - .env
     environment:
-      DATABASE_URL: postgresql://postgres:postgres@db:5432/kcapp?schema=public
+      DATABASE_URL: postgresql://postgres:***@db:5432/kcapp?schema=public
       PORT: "3000"
       GOOGLE_APPLICATION_CREDENTIALS: /app/serviceAccount.json
       APP_BASE_URL: http://localhost:3010
+      WEB_CLIENT_DIR: /app/web
     ports:
       - "3010:3000"
     volumes:
       # Firebase service account — kept out of the image, mounted read-only.
-      - ./backend/serviceAccount.json:/app/serviceAccount.json:ro
+      - ./serviceAccount.json:/app/serviceAccount.json:ro
+      # Pre-built Flutter web bundle, built separately in the KC-APP client
+      # repo (flutter build web --release) and mounted read-only here.
+      # Set WEB_CLIENT_BUILD_PATH (e.g. in .env) to that build/web directory;
+      # defaults to a sibling ../KC-APP checkout.
+      - ${WEB_CLIENT_BUILD_PATH:-../KC-APP/client/app/build/web}:/app/web:ro
 
 volumes:
   pgdata: