fix: use script file instead of heredoc in Dockerfile

backend/Dockerfile

@@ -12,32 +12,7 @@ COPY requirements.txt .
 RUN pip install --no-cache-dir -r requirements.txt
 
 COPY . .
-
-# Create startup script
-RUN cat > /start.sh << 'EOF'
-#!/bin/bash
-set -e
-echo "Waiting for database..."
-until python -c "
-import psycopg2, os
-try:
-    conn = psycopg2.connect(os.environ.get('DATABASE_URL', 'postgresql://servesync:servesync@db:5432/servesync'))
-    conn.close()
-    print('DB ready')
-except Exception as e:
-    print(f'DB not ready: {e}')
-    exit(1)
-"; do
-  sleep 2
-done
-
-echo "Running seed..."
-python seed.py || echo "Seed already ran or error (continuing)"
-
-echo "Starting server..."
-exec uvicorn app.main:app --host 0.0.0.0 --port 8000 --reload
-EOF
-RUN chmod +x /start.sh
+RUN chmod +x /app/start.sh
 
 EXPOSE 8000
-CMD ["/start.sh"]
+CMD ["/app/start.sh"]