feat(api): add log webhook notification service

Implement webhook notifications for log error threshold alerts with
configurable thresholds, time windows, and cooldown periods.

- Add LogWebhookService with Redis-backed configuration storage
- Add admin endpoints for webhook config management (GET/PUT)
- Trigger webhook notifications when error count exceeds threshold
- Support status code threshold and error message detection
- Include sample log record data in webhook payload

internal/api/log_webhook_handler_test.go

@@ -0,0 +1,112 @@
+package api
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/alicebob/miniredis/v2"
+	"github.com/ez-api/ez-api/internal/model"
+	"github.com/ez-api/ez-api/internal/service"
+	"github.com/gin-gonic/gin"
+	"github.com/redis/go-redis/v9"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+)
+
+func newTestHandlerWithWebhook(t *testing.T) (*Handler, *miniredis.Miniredis) {
+	t.Helper()
+	gin.SetMode(gin.TestMode)
+
+	dsn := fmt.Sprintf("file:%s?mode=memory&cache=shared", t.Name())
+	db, err := gorm.Open(sqlite.Open(dsn), &gorm.Config{})
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	if err := db.AutoMigrate(&model.LogRecord{}); err != nil {
+		t.Fatalf("migrate: %v", err)
+	}
+
+	mr := miniredis.RunT(t)
+	rdb := redis.NewClient(&redis.Options{Addr: mr.Addr()})
+	sync := service.NewSyncService(rdb)
+	return NewHandler(db, sync, nil, rdb), mr
+}
+
+func TestLogWebhookConfigCRUD(t *testing.T) {
+	h, _ := newTestHandlerWithWebhook(t)
+
+	r := gin.New()
+	r.GET("/admin/logs/webhook", h.GetLogWebhookConfig)
+	r.PUT("/admin/logs/webhook", h.UpdateLogWebhookConfig)
+
+	reqBody := service.LogWebhookConfig{
+		Enabled:             true,
+		URL:                 "https://example.com/webhook",
+		Secret:              "s1",
+		Threshold:           3,
+		WindowSeconds:       60,
+		CooldownSeconds:     120,
+		StatusCodeThreshold: 500,
+	}
+	payload, _ := json.Marshal(reqBody)
+
+	req := httptest.NewRequest(http.MethodPut, "/admin/logs/webhook", bytes.NewReader(payload))
+	req.Header.Set("Content-Type", "application/json")
+	rr := httptest.NewRecorder()
+	r.ServeHTTP(rr, req)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d body=%s", rr.Code, rr.Body.String())
+	}
+
+	getReq := httptest.NewRequest(http.MethodGet, "/admin/logs/webhook", nil)
+	getRR := httptest.NewRecorder()
+	r.ServeHTTP(getRR, getReq)
+	if getRR.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d body=%s", getRR.Code, getRR.Body.String())
+	}
+
+	var got service.LogWebhookConfig
+	if err := json.Unmarshal(getRR.Body.Bytes(), &got); err != nil {
+		t.Fatalf("decode response: %v", err)
+	}
+	if !got.Enabled || got.URL == "" || got.Threshold != 3 {
+		t.Fatalf("unexpected webhook config: %+v", got)
+	}
+	if got.Secret != "s1" {
+		t.Fatalf("expected secret s1, got %q", got.Secret)
+	}
+}
+
+func TestLogWebhookConfigDisableClears(t *testing.T) {
+	h, mr := newTestHandlerWithWebhook(t)
+
+	r := gin.New()
+	r.PUT("/admin/logs/webhook", h.UpdateLogWebhookConfig)
+
+	seed := service.LogWebhookConfig{Enabled: true, URL: "https://example.com"}
+	payload, _ := json.Marshal(seed)
+	req := httptest.NewRequest(http.MethodPut, "/admin/logs/webhook", bytes.NewReader(payload))
+	req.Header.Set("Content-Type", "application/json")
+	rr := httptest.NewRecorder()
+	r.ServeHTTP(rr, req)
+	if rr.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d body=%s", rr.Code, rr.Body.String())
+	}
+
+	clear := service.LogWebhookConfig{Enabled: false}
+	clearPayload, _ := json.Marshal(clear)
+	clearReq := httptest.NewRequest(http.MethodPut, "/admin/logs/webhook", bytes.NewReader(clearPayload))
+	clearReq.Header.Set("Content-Type", "application/json")
+	clearRR := httptest.NewRecorder()
+	r.ServeHTTP(clearRR, clearReq)
+	if clearRR.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d body=%s", clearRR.Code, clearRR.Body.String())
+	}
+	if mr.Exists("meta:log:webhook") {
+		t.Fatalf("expected webhook config to be cleared")
+	}
+}