Add persistent volume for uploads to survive redeployments

Files uploaded by users were lost on every container rebuild.
Named volume uploads_data mounts to /app/uploads and is managed by Coolify.

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

docker-compose.yml

@@ -6,6 +6,8 @@ services:
     environment:
       - PORT=3001
       - STORAGE_URL=https://backend.prosapp.co/uploads
+    volumes:
+      - uploads_data:/app/uploads
 
   admin:
     build:
@@ -16,3 +18,6 @@ services:
       - '5173:3000'
     environment:
       - PORT=3000
+
+volumes:
+  uploads_data: