Force production mode build and cache invalidation

- Add --mode production to Vite build to ensure import.meta.env.DEV is false
- Add timestamp comment to invalidate Docker cache

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

Dockerfile

@@ -3,6 +3,8 @@ FROM node:20-slim
 # Set noninteractive installation
 ENV DEBIAN_FRONTEND=noninteractive
 
+# Build timestamp to force cache invalidation: 2026-01-11T11:00
+
 # Install build dependencies
 RUN apt-get update && apt-get install -y \
     curl \
@@ -29,8 +31,8 @@ RUN npm install --omit=dev && \
 # Build jison parsers (required for the game) - use global tsx directly
 RUN tsx tools/buildJisonParser.ts
 
-# Build frontend (generates dist folder)
-RUN cd app && npm run build
+# Build frontend (generates dist folder) - explicitly set production mode
+RUN cd app && npm run build -- --mode production
 
 # Build backend with esbuild (handles ESM imports without .js extensions)
 RUN esbuild backend/src/server.ts --bundle --platform=node --target=node20 --format=esm --outfile=backend/dist/server.js --external:express --external:socket.io --external:cors --external:dotenv --external:uuid