fix docker build: use node for vite, bun for runtime

Bun has compatibility issues with Vite v7 + Tailwind v4 during the
build step (error during build: undefined). Multi-stage build uses
Node.js for the Vite build, Bun for the production server.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -1,16 +1,19 @@
-FROM oven/bun:1 AS base
+FROM node:22-slim AS build
 WORKDIR /app
-
+RUN npm install -g bun
 COPY package.json bun.lock* ./
 RUN bun install --frozen-lockfile
-
 COPY . .
-RUN DEBUG=vite:* bun run build 2>&1
+RUN npx vite build
 
+FROM oven/bun:1
+WORKDIR /app
+COPY package.json bun.lock* ./
+RUN bun install --frozen-lockfile --production
+COPY --from=build /app/dist ./dist
+COPY server ./server
 EXPOSE 3000
 ENV DATA_DIR=/data
 ENV PORT=3000
-
 VOLUME ["/data"]
-
 CMD ["bun", "run", "server/index.tsx"]