Fix Docker build: include devDependencies for frontend build

Dockerfile

@@ -30,7 +30,7 @@ RUN npm ci --only=production
 
 # Build the frontend
 COPY frontend ./frontend
-RUN cd frontend && npm install && npm run build
+RUN cd frontend && npm install --include=dev && npm run build
 
 # Copy backend package files and install backend dependencies
 COPY backend/package*.json ./backend/