Fix Dockerfile: Use npm install instead of npm ci (package-lock.json missing)

backend/Dockerfile.prod

@@ -2,9 +2,9 @@ FROM node:20-alpine AS builder
 
 WORKDIR /app
 
-# Install dependencies
+# Install dependencies (including dev dependencies for build)
 COPY package*.json ./
-RUN npm ci --only=production && npm cache clean --force
+RUN npm install && npm cache clean --force
 
 # Copy source
 COPY . .
@@ -19,7 +19,7 @@ WORKDIR /app
 
 # Install only production dependencies
 COPY package*.json ./
-RUN npm ci --only=production && npm cache clean --force
+RUN npm install --omit=dev && npm cache clean --force
 
 # Copy built files
 COPY --from=builder /app/dist ./dist