feat(t15): 健康检查端点 /health（pg/redis/队列四态，DOWN 返503）

- DistQueueMapper: +countByStatus (GROUP BY status 一次拿全)
- HealthService(新): 聚合 pg 连通/redis ping/队列四态，status UP/DEGRADED/DOWN
- HealthController(新): GET /health，DOWN 返 503 便 LB 摘流；免租户鉴权(PathWhitelist)
- 联调：status=UP，pg/redis=UP，distQueue 四态 0，HTTP 200

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

src/main/java/com/imutil/common/HealthService.java

@@ -0,0 +1,95 @@
+package com.imutil.common;
+
+import com.imutil.mapper.DistQueueMapper;
+import lombok.extern.slf4j.Slf4j;
+import org.noear.solon.annotation.Component;
+import org.noear.solon.annotation.Inject;
+import redis.clients.jedis.Jedis;
+import redis.clients.jedis.JedisPool;
+
+import java.time.OffsetDateTime;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * 健康检查服务（对齐设计：监控告警 - 中间件连通、dist_queue 堆积）
+ * <p>
+ * 聚合 PG / Redis 连通性与分发队列状态分布，输出整体 status：
+ *   - UP：PG + Redis 均连通
+ *   - DEGRADED：PG 连通、Redis 异常（限流 fail-open、缓存降级，核心链路仍可用）
+ *   - DOWN：PG 异常（消息落库不可用，核心受损）
+ * <p>
+ * 队列 pending/processing/dead 计数供运维判断是否需干预：
+ *   - pending 持续上涨 → worker 处理不过去，考虑扩容
+ *   - processing 长期不归零且无 done 增长 → 工作线程可能卡死
+ *   - dead 积累 → 需排查死信或重发
+ *
+ * @author imutil
+ */
+@Slf4j
+@Component
+public class HealthService {
+
+    @Inject
+    private DistQueueMapper distQueueMapper;
+
+    @Inject
+    private JedisPool jedisPool;
+
+    /**
+     * 采集健康指标
+     *
+     * @return 含 status / pg / redis / distQueue / timestamp
+     */
+    public Map<String, Object> health() {
+        Map<String, Object> distQueue = new LinkedHashMap<>();
+        boolean pgUp;
+        try {
+            List<Map<String, Object>> rows = distQueueMapper.countByStatus();
+            // 四态计数初始化为 0（无记录的状态不出现在 GROUP BY 结果中）
+            long[] cnt = new long[4];
+            for (Map<String, Object> row : rows) {
+                int st = ((Number) row.get("status")).intValue();
+                long c = ((Number) row.get("cnt")).longValue();
+                if (st >= 0 && st < 4) {
+                    cnt[st] = c;
+                }
+            }
+            distQueue.put("pending", cnt[0]);
+            distQueue.put("processing", cnt[1]);
+            distQueue.put("done", cnt[2]);
+            distQueue.put("dead", cnt[3]);
+            pgUp = true;
+        } catch (Exception e) {
+            log.warn("健康检查 PG 查询失败 : {}", e.getMessage());
+            distQueue.put("error", e.getMessage());
+            pgUp = false;
+        }
+
+        boolean redisUp;
+        try (Jedis j = jedisPool.getResource()) {
+            redisUp = "PONG".equals(j.ping());
+        } catch (Exception e) {
+            log.warn("健康检查 Redis ping 失败 : {}", e.getMessage());
+            redisUp = false;
+        }
+
+        String status;
+        if (pgUp && redisUp) {
+            status = "UP";
+        } else if (pgUp) {
+            status = "DEGRADED";
+        } else {
+            status = "DOWN";
+        }
+
+        Map<String, Object> r = new LinkedHashMap<>();
+        r.put("status", status);
+        r.put("pg", pgUp ? "UP" : "DOWN");
+        r.put("redis", redisUp ? "UP" : "DOWN");
+        r.put("distQueue", distQueue);
+        r.put("timestamp", OffsetDateTime.now().toString());
+        return r;
+    }
+}

src/main/java/com/imutil/controller/HealthController.java

@@ -0,0 +1,36 @@
+package com.imutil.controller;
+
+import com.imutil.common.HealthService;
+import com.imutil.model.Result;
+import org.noear.solon.annotation.Controller;
+import org.noear.solon.annotation.Inject;
+import org.noear.solon.annotation.Mapping;
+import org.noear.solon.core.handle.Context;
+import org.noear.solon.core.handle.MethodType;
+
+import java.util.Map;
+
+/**
+ * 健康检查端点（运维 / LB 探针）
+ * <p>
+ * GET /health：返回 PG/Redis 连通 + 分发队列四态计数。
+ * 免租户鉴权（见 {@link com.imutil.common.PathWhitelist}）。
+ * HTTP 状态码：200 = UP/DEGRADED（核心可用）；503 = DOWN（PG 异常，核心受损），
+ * 便于 LB/k8s 探针据状态码摘流。
+ *
+ * @author imutil
+ */
+@Controller
+public class HealthController {
+
+    @Inject
+    private HealthService healthService;
+
+    @Mapping(value = "/health", method = MethodType.GET)
+    public void health(Context ctx) throws Throwable {
+        Map<String, Object> h = healthService.health();
+        // DOWN 返回 503，便探针摘流；UP/DEGRADED 返回 200
+        ctx.status("DOWN".equals(h.get("status")) ? 503 : 200);
+        ctx.render(Result.ok(h));
+    }
+}

src/main/java/com/imutil/mapper/DistQueueMapper.java

@@ -78,4 +78,12 @@ public interface DistQueueMapper extends BaseMapper<DistQueue> {
             "locked_by = NULL, locked_at = NULL, updated_at = now() " +
             "WHERE id = #{id} AND status = 3")
     int redeliverDead(@Param("id") Long id);
+
+    /**
+     * 按状态聚合计数（健康检查/监控用，一次扫描拿全状态分布）
+     *
+     * @return 每项含 status（0=pending/1=processing/2=done/3=dead）与 cnt
+     */
+    @org.apache.ibatis.annotations.Select("SELECT status, count(*) AS cnt FROM dist_queue GROUP BY status")
+    java.util.List<java.util.Map<String, Object>> countByStatus();
 }