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/provider/client_test.go

@@ -13,12 +13,13 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
 
 	"nex/backend/internal/conversion"
 )
 
 func TestNewClient(t *testing.T) {
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	require.NotNil(t, client)
 	assert.NotNil(t, client.httpClient)
 	assert.Equal(t, 4096, client.streamCfg.InitialBufferSize)
@@ -44,7 +45,7 @@ func TestClient_Send_Success(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:    server.URL + "/v1/chat/completions",
 		Method: "POST",
@@ -68,7 +69,7 @@ func TestClient_Send_ErrorResponse(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -82,7 +83,7 @@ func TestClient_Send_ErrorResponse(t *testing.T) {
 }
 
 func TestClient_Send_ConnectionError(t *testing.T) {
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:    "http://localhost:1/v1/chat/completions",
 		Method: "POST",
@@ -99,7 +100,7 @@ func TestClient_SendStream_CreatesChannel(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -121,7 +122,7 @@ func TestClient_SendStream_ErrorResponse(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -150,7 +151,7 @@ func TestClient_SendStream_SSEEvents(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -188,7 +189,7 @@ func TestClient_SendStream_ContextCancellation(t *testing.T) {
 	defer server.Close()
 
 	ctx, cancel := context.WithCancel(context.Background())
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -218,7 +219,7 @@ func TestClient_Send_EmptyBody(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/models",
 		Method:  "GET",
@@ -246,7 +247,7 @@ func TestClient_SendStream_SlowSSE(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -287,7 +288,7 @@ func TestClient_SendStream_SplitSSEEvents(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",
@@ -375,7 +376,7 @@ func TestClient_SendStream_MidStreamNetworkError(t *testing.T) {
 	}))
 	defer server.Close()
 
-	client := NewClient()
+	client := NewClient(zap.NewNop())
 	spec := conversion.HTTPRequestSpec{
 		URL:     server.URL + "/v1/chat/completions",
 		Method:  "POST",