fix(auth): 为登录链路增加有界超时

为 PostgreSQL 连接、就绪检查和本地登录设置分层超时，数据库不可用时返回稳定 503 错误码并记录无凭据的连接池统计。

前端登录在 10 秒后取消请求并兼容调用方 AbortSignal，Nginx 登录精确路由限制上游为 15 秒，同时更新 OpenAPI 和回归测试。

apps/api/internal/httpapi/handlers.go

@@ -17,6 +17,14 @@ import (
 	"github.com/easyai/easyai-ai-gateway/apps/api/internal/store"
 )
 
+const (
+	postgresReadinessTimeout  = 2 * time.Second
+	localLoginStoreTimeout    = 5 * time.Second
+	errorCodePostgresDown     = "POSTGRES_UNAVAILABLE"
+	errorCodeAuthStoreDown    = "AUTH_STORE_UNAVAILABLE"
+	authStoreUnavailableError = "authentication service temporarily unavailable"
+)
+
 // health godoc
 // @Summary 健康检查
 // @Description 返回服务进程、运行环境和身份模式，供负载均衡或人工排障使用。
@@ -42,8 +50,11 @@ func (s *Server) health(w http.ResponseWriter, r *http.Request) {
 // @Failure 503 {object} ErrorEnvelope
 // @Router /readyz [get]
 func (s *Server) ready(w http.ResponseWriter, r *http.Request) {
-	if err := s.store.Ping(r.Context()); err != nil {
-		writeError(w, http.StatusServiceUnavailable, "postgres unavailable")
+	ctx, cancel := context.WithTimeout(r.Context(), postgresReadinessTimeout)
+	defer cancel()
+	if err := s.store.Ping(ctx); err != nil {
+		s.logPostgresUnavailable("postgres readiness check failed")
+		writeError(w, http.StatusServiceUnavailable, "postgres unavailable", errorCodePostgresDown)
 		return
 	}
 	writeJSON(w, http.StatusOK, map[string]any{"ok": true})
@@ -121,6 +132,7 @@ func (s *Server) register(w http.ResponseWriter, r *http.Request) {
 // @Failure 401 {object} ErrorEnvelope
 // @Failure 403 {object} ErrorEnvelope
 // @Failure 500 {object} ErrorEnvelope
+// @Failure 503 {object} ErrorEnvelope
 // @Router /api/v1/auth/login [post]
 func (s *Server) login(w http.ResponseWriter, r *http.Request) {
 	var input store.LocalLoginInput
@@ -128,12 +140,19 @@ func (s *Server) login(w http.ResponseWriter, r *http.Request) {
 		writeError(w, http.StatusBadRequest, "invalid json body")
 		return
 	}
-	user, err := s.store.AuthenticateLocalUser(r.Context(), input)
+	ctx, cancel := context.WithTimeout(r.Context(), localLoginStoreTimeout)
+	defer cancel()
+	user, err := s.store.AuthenticateLocalUser(ctx, input)
 	if err != nil {
 		if errors.Is(err, store.ErrInvalidCredentials) {
 			writeError(w, http.StatusUnauthorized, "invalid account or password")
 			return
 		}
+		if store.IsPostgresUnavailable(err) {
+			s.logPostgresUnavailable("login authentication store unavailable")
+			writeError(w, http.StatusServiceUnavailable, authStoreUnavailableError, errorCodeAuthStoreDown)
+			return
+		}
 		s.logger.Error("login local user failed", "error", err)
 		writeError(w, http.StatusInternalServerError, "login failed")
 		return
@@ -145,6 +164,22 @@ func (s *Server) login(w http.ResponseWriter, r *http.Request) {
 	s.writeAuthResponse(w, http.StatusOK, user)
 }
 
+func (s *Server) logPostgresUnavailable(message string) {
+	if s.logger == nil || s.store == nil || s.store.Pool() == nil {
+		return
+	}
+	statistics := s.store.Pool().Stat()
+	s.logger.Error(message,
+		"error_category", "postgres_unavailable",
+		"postgres_pool_max_connections", statistics.MaxConns(),
+		"postgres_pool_total_connections", statistics.TotalConns(),
+		"postgres_pool_acquired_connections", statistics.AcquiredConns(),
+		"postgres_pool_idle_connections", statistics.IdleConns(),
+		"postgres_pool_empty_acquire_count", statistics.EmptyAcquireCount(),
+		"postgres_pool_canceled_acquire_count", statistics.CanceledAcquireCount(),
+	)
+}
+
 func (s *Server) localIdentityEnabled() bool {
 	mode := strings.ToLower(strings.TrimSpace(s.cfg.IdentityMode))
 	return mode == "" || mode == "standalone" || mode == "hybrid"