Add Dockerfile and finalize build config

Dockerfile

@@ -0,0 +1,37 @@
+# ---- Build stage ----
+FROM node:22-alpine AS builder
+
+WORKDIR /app
+
+# Install pnpm
+RUN corepack enable && corepack prepare pnpm@latest --activate
+
+# Copy dependency manifests
+COPY package.json pnpm-lock.yaml pnpm-workspace.yaml ./
+COPY .npmrc ./
+
+# Install dependencies
+RUN pnpm install --frozen-lockfile
+
+# Copy source
+COPY . .
+
+# Build the app
+RUN pnpm run build
+
+# ---- Production stage ----
+FROM node:22-alpine AS runner
+
+WORKDIR /app
+
+# Copy built app
+COPY --from=builder /app/build ./build
+COPY --from=builder /app/package.json ./
+COPY --from=builder /app/node_modules ./node_modules
+
+# Expose the port
+ENV PORT=3000
+EXPOSE 3000
+
+# Start the server
+CMD ["node", "build/index.js"]