fix: pin PORT per service to isolate from global Coolify env var

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

docker-compose.yml

@@ -3,6 +3,8 @@ services:
     build: ./backend
     ports:
       - '3001:3001'
+    environment:
+      - PORT=3001
 
   admin:
     build:
@@ -10,4 +12,6 @@ services:
       args:
         - NEXT_PUBLIC_API_URL=https://backend.prosapp.co/api/v1
     ports:
-      - '5173:3001'
+      - '5173:3000'
+    environment:
+      - PORT=3000