build(confidence-engine): add production container packaging

Dockerfile

@@ -0,0 +1,45 @@
+# ── Stage 1: Build ─────────────────────────────────────────────────────
+FROM node:22-alpine AS builder
+
+WORKDIR /app
+
+ENV NEXT_PUBLIC_SUPABASE_URL="" \
+    NEXT_PUBLIC_SUPABASE_ANON_KEY=""
+
+COPY package.json package-lock.json* yarn.lock* pnpm-lock.yaml* ./
+
+RUN corepack enable && \
+    if [ -f pnpm-lock.yaml ]; then \
+        corepack prepare pnpm@latest --activate; \
+        pnpm install --frozen-lockfile; \
+    elif [ -f yarn.lock ]; then \
+        yarn install --frozen-lockfile; \
+    else \
+        npm ci; \
+    fi
+
+COPY . .
+
+RUN NEXT_PUBLIC_SUPABASE_URL=${NEXT_PUBLIC_SUPABASE_URL} \
+    NEXT_PUBLIC_SUPABASE_ANON_KEY=${NEXT_PUBLIC_SUPABASE_ANON_KEY} \
+    next build
+
+# ── Stage 2: Production runtime ────────────────────────────────────────
+FROM node:22-alpine AS runner
+
+WORKDIR /app
+
+ENV NODE_ENV=production \
+    NEXT_TELEMETRY_DISABLED=1 \
+    PORT=3000 \
+    HOSTNAME="0.0.0.0"
+
+COPY --from=builder /app/public ./public
+COPY --from=builder --chown=node:node /app/.next/standalone ./
+COPY --from=builder --chown=node:node /app/.next/static ./.next/static
+
+USER node
+
+EXPOSE 3000
+
+CMD ["node", "server.js"]