feat: add web Dockerfile for Railway deployment

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

web/Dockerfile

@@ -0,0 +1,19 @@
+FROM oven/bun:1 AS builder
+
+WORKDIR /app
+COPY package.json bun.lock ./
+RUN bun install --frozen-lockfile
+
+COPY . .
+RUN bun run build
+
+FROM oven/bun:1
+
+WORKDIR /app
+COPY --from=builder /app/build ./build
+COPY --from=builder /app/package.json .
+COPY --from=builder /app/node_modules ./node_modules
+
+EXPOSE 3000
+ENV PORT=3000
+CMD ["bun", "build/index.js"]