refactor: 后端日志系统重构

- 新增模块化日志器（pkg/logger/module.go）
- 新增 GORM 日志适配器
- 统一日志入口，移除所有 zap.L() 全局 logger 调用
- 字段标准化
- 启动阶段使用结构化日志
- 更新所有相关测试

backend/internal/handler/middleware/logging.go

@@ -5,9 +5,10 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"go.uber.org/zap"
+
+	pkglogger "nex/backend/pkg/logger"
 )
 
-// Logging 日志中间件
 func Logging(logger *zap.Logger) gin.HandlerFunc {
 	return func(c *gin.Context) {
 		start := time.Now()
@@ -15,12 +16,17 @@ func Logging(logger *zap.Logger) gin.HandlerFunc {
 		query := c.Request.URL.RawQuery
 
 		requestID, _ := c.Get(RequestIDKey)
+		var requestIDStr string
+		if id, ok := requestID.(string); ok {
+			requestIDStr = id
+		}
+		
 		logger.Info("请求开始",
-			zap.String("method", c.Request.Method),
-			zap.String("path", path),
-			zap.String("query", query),
-			zap.String("client_ip", c.ClientIP()),
-			zap.Any("request_id", requestID),
+			pkglogger.Method(c.Request.Method),
+			pkglogger.Path(path),
+			pkglogger.Query(query),
+			pkglogger.ClientIP(c.ClientIP()),
+			pkglogger.RequestID(requestIDStr),
 		)
 
 		c.Next()
@@ -29,12 +35,12 @@ func Logging(logger *zap.Logger) gin.HandlerFunc {
 		statusCode := c.Writer.Status()
 
 		logger.Info("请求结束",
-			zap.Int("status", statusCode),
-			zap.String("method", c.Request.Method),
-			zap.String("path", path),
-			zap.Duration("latency", latency),
-			zap.Int("body_size", c.Writer.Size()),
-			zap.Any("request_id", requestID),
+			pkglogger.StatusCode(statusCode),
+			pkglogger.Method(c.Request.Method),
+			pkglogger.Path(path),
+			pkglogger.Latency(latency),
+			pkglogger.BodySize(c.Writer.Size()),
+			pkglogger.RequestID(requestIDStr),
 		)
 	}
 }

backend/internal/handler/proxy_handler.go

@@ -16,6 +16,7 @@ import (
 	"nex/backend/internal/provider"
 	"nex/backend/internal/service"
 	"nex/backend/pkg/modelid"
+	pkglogger "nex/backend/pkg/logger"
 )
 
 // ProxyHandler 统一代理处理器
@@ -29,14 +30,14 @@ type ProxyHandler struct {
 }
 
 // NewProxyHandler 创建统一代理处理器
-func NewProxyHandler(engine *conversion.ConversionEngine, client provider.ProviderClient, routingService service.RoutingService, providerService service.ProviderService, statsService service.StatsService) *ProxyHandler {
+func NewProxyHandler(engine *conversion.ConversionEngine, client provider.ProviderClient, routingService service.RoutingService, providerService service.ProviderService, statsService service.StatsService, logger *zap.Logger) *ProxyHandler {
 	return &ProxyHandler{
 		engine:          engine,
 		client:          client,
 		routingService:  routingService,
 		providerService: providerService,
 		statsService:    statsService,
-		logger:          zap.L(),
+		logger:          pkglogger.WithModule(logger, "handler.proxy"),
 	}
 }
 
@@ -331,7 +332,7 @@ func (h *ProxyHandler) handleModelInfo(c *gin.Context, unifiedID string, adapter
 	// 使用 adapter 编码返回
 	body, err := adapter.EncodeModelInfoResponse(modelInfo)
 	if err != nil {
-		h.logger.Error("编码 ModelInfo 响应失败", zap.String("error", err.Error()))
+		h.logger.Error("编码 ModelInfo 响应失败", zap.Error(err))
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "编码响应失败"})
 		return
 	}

backend/internal/handler/proxy_handler_test.go

@@ -12,6 +12,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"go.uber.org/mock/gomock"
+	"go.uber.org/zap"
 
 	"nex/backend/internal/conversion"
 	"nex/backend/internal/conversion/anthropic"
@@ -31,7 +32,7 @@ func init() {
 func setupProxyEngine(t *testing.T) *conversion.ConversionEngine {
 	t.Helper()
 	registry := conversion.NewMemoryRegistry()
-	engine := conversion.NewConversionEngine(registry, nil)
+	engine := conversion.NewConversionEngine(registry, zap.NewNop())
 	require.NoError(t, registry.Register(openai.NewAdapter()))
 	require.NoError(t, registry.Register(anthropic.NewAdapter()))
 	return engine
@@ -44,6 +45,7 @@ func newTestProxyHandler(engine *conversion.ConversionEngine, client *mocks.Mock
 		routingSvc,
 		providerSvc,
 		statsSvc,
+		zap.NewNop(),
 	)
 }
 
@@ -499,7 +501,7 @@ func TestProxyHandler_HandleStream_CreateStreamConverterError(t *testing.T) {
 	defer ctrl.Finish()
 
 	registry := conversion.NewMemoryRegistry()
-	engine := conversion.NewConversionEngine(registry, nil)
+	engine := conversion.NewConversionEngine(registry, zap.NewNop())
 	err := registry.Register(openai.NewAdapter())
 	require.NoError(t, err)
 
@@ -527,7 +529,7 @@ func TestProxyHandler_HandleStream_ConvertRequestError(t *testing.T) {
 	defer ctrl.Finish()
 
 	registry := conversion.NewMemoryRegistry()
-	engine := conversion.NewConversionEngine(registry, nil)
+	engine := conversion.NewConversionEngine(registry, zap.NewNop())
 	require.NoError(t, registry.Register(openai.NewAdapter()))
 
 	routingSvc := mocks.NewMockRoutingService(ctrl)
@@ -554,7 +556,7 @@ func TestProxyHandler_HandleNonStream_ConvertResponseError(t *testing.T) {
 	defer ctrl.Finish()
 
 	registry := conversion.NewMemoryRegistry()
-	engine := conversion.NewConversionEngine(registry, nil)
+	engine := conversion.NewConversionEngine(registry, zap.NewNop())
 	require.NoError(t, registry.Register(openai.NewAdapter()))
 	require.NoError(t, registry.Register(anthropic.NewAdapter()))
 
@@ -623,7 +625,7 @@ func TestProxyHandler_ForwardPassthrough_CrossProtocol(t *testing.T) {
 	defer ctrl.Finish()
 
 	registry := conversion.NewMemoryRegistry()
-	engine := conversion.NewConversionEngine(registry, nil)
+	engine := conversion.NewConversionEngine(registry, zap.NewNop())
 	require.NoError(t, registry.Register(openai.NewAdapter()))
 
 	anthropicAdapter := anthropic.NewAdapter()