chore(deploy): expose flashcard on host port 4000 (4000:3000)

compose.yaml

@@ -9,8 +9,9 @@ services:
     image: flashcard:local
     container_name: flashcard
     restart: unless-stopped
+    # host:container — exposed on 4000 on the Dockge host, app listens on 3000 inside.
     ports:
-      - "3000:3000"
+      - "4000:3000"
     volumes:
       - flashcard-data:/data
     environment:
@@ -19,9 +20,9 @@ services:
       DB_PATH: /data/flashcard.db
 
       # URL where users reach the app. Used in verification / reset / invite emails.
-      # CHANGE THIS to your real address, e.g. http://192.168.1.50:3000
+      # CHANGE THIS to your real address, e.g. http://192.168.1.50:4000
       # or https://flashcards.hausmans.cloud once behind a reverse proxy.
-      APP_URL: "http://CHANGE-ME:3000"
+      APP_URL: "http://CHANGE-ME:4000"
 
       # Cookie security. Keep "false" when serving over plain HTTP — otherwise the
       # browser drops the session cookie and login silently fails. Set to "true"