Add /api/health and harden Docker deploy script for API route rollout.

404 on /api/ai indicates stale container; deploy script now uses --no-cache, stops PM2/port conflicts, and verifies /api/health.

Co-authored-by: Cursor <cursoragent@cursor.com>

Dockerfile

@@ -27,6 +27,7 @@ RUN addgroup --system --gid 1001 nodejs \
 # standalone 产物
 COPY --from=builder /app/.next/standalone ./
 COPY --from=builder /app/.next/static ./.next/static
+COPY --from=builder /app/public ./public
 # 卦辞 Markdown（运行时读取）
 COPY --from=builder /app/content ./content