fix(docker): slim runner stage — native deps in separate build stage (567MB → 248MB)

Dockerfile

@@ -18,6 +18,16 @@ COPY . .
 # Build the frontend
 RUN npm run build
 
+# Native modules stage — compile better-sqlite3 in a dedicated stage
+FROM node:20-alpine AS native-deps
+
+WORKDIR /app
+
+COPY package.json package-lock.json* ./
+
+RUN apk add --no-cache python3 make g++
+RUN npm ci --omit=dev
+
 # Production stage
 FROM node:20-alpine AS runner
 
@@ -51,9 +61,8 @@ COPY --from=builder /app/package.json /app/package-lock.json* ./
 COPY --from=builder /app/dist ./dist
 COPY --from=builder /app/server ./server
 
-# Install build tools for native modules + production dependencies
+# Copy compiled native modules from native-deps stage (no build tools in final image)
-RUN apk add --no-cache python3 make g++
+COPY --from=native-deps /app/node_modules ./node_modules
-RUN npm ci --omit=dev
 
 # Expose backend port
 EXPOSE 3001