feat: 配置 golangci-lint 静态分析并修复存量违规

- 新增 backend/.golangci.yml 配置 12 个 linter（forbidigo、errorlint、errcheck、staticcheck、revive、gocritic、gosec、bodyclose、noctx、nilerr、goimports、gocyclo）
- 新增 lefthook.yml 配置 pre-commit hook 自动运行 lint
- 修复存量代码违规：errors.Is/As 替换、zap.Error 替换、import 排序、errcheck 修复
- 更新 README 补充编码规范说明
- 归档 backend-code-lint 变更

backend/tests/integration/integration_test.go

@@ -7,16 +7,17 @@ import (
 	"testing"
 	"time"
 
-	"github.com/gin-gonic/gin"
-	"github.com/stretchr/testify/assert"
-	"go.uber.org/zap"
-	"gorm.io/gorm"
-
 	"nex/backend/internal/domain"
 	"nex/backend/internal/handler"
 	"nex/backend/internal/handler/middleware"
 	"nex/backend/internal/repository"
 	"nex/backend/internal/service"
+
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.uber.org/zap"
+	"gorm.io/gorm"
 )
 
 func init() {
@@ -97,7 +98,7 @@ func TestOpenAI_CompleteFlow(t *testing.T) {
 	r.ServeHTTP(w, req)
 	assert.Equal(t, 201, w.Code)
 	var createdModel domain.Model
-	json.Unmarshal(w.Body.Bytes(), &createdModel)
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &createdModel))
 	assert.NotEmpty(t, createdModel.ID)
 
 	// 3. 列出 Provider
@@ -106,7 +107,7 @@ func TestOpenAI_CompleteFlow(t *testing.T) {
 	r.ServeHTTP(w, req)
 	assert.Equal(t, 200, w.Code)
 	var providers []domain.Provider
-	json.Unmarshal(w.Body.Bytes(), &providers)
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &providers))
 	assert.Len(t, providers, 1)
 	assert.Equal(t, "sk-test-key", providers[0].APIKey)
 
@@ -116,7 +117,7 @@ func TestOpenAI_CompleteFlow(t *testing.T) {
 	r.ServeHTTP(w, req)
 	assert.Equal(t, 200, w.Code)
 	var models []domain.Model
-	json.Unmarshal(w.Body.Bytes(), &models)
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &models))
 	assert.Len(t, models, 1)
 	assert.Equal(t, "gpt-4", models[0].ModelName)
 
@@ -163,7 +164,7 @@ func TestAnthropic_ModelCreation(t *testing.T) {
 	r.ServeHTTP(w, req)
 	assert.Equal(t, 201, w.Code)
 	var createdModel domain.Model
-	json.Unmarshal(w.Body.Bytes(), &createdModel)
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &createdModel))
 
 	// 验证创建成功
 	w = httptest.NewRecorder()
@@ -194,9 +195,9 @@ func TestStats_RecordingAndQuery(t *testing.T) {
 
 	// 直接通过 repository 记录统计（模拟代理请求后的统计记录）
 	statsRepo := repository.NewStatsRepository(db)
-	statsRepo.Record("p1", "gpt-4")
-	statsRepo.Record("p1", "gpt-4")
-	statsRepo.Record("p1", "gpt-4")
+	require.NoError(t, statsRepo.Record("p1", "gpt-4"))
+	require.NoError(t, statsRepo.Record("p1", "gpt-4"))
+	require.NoError(t, statsRepo.Record("p1", "gpt-4"))
 
 	// 查询统计
 	w = httptest.NewRecorder()
@@ -205,7 +206,7 @@ func TestStats_RecordingAndQuery(t *testing.T) {
 	assert.Equal(t, 200, w.Code)
 
 	var stats []domain.UsageStats
-	json.Unmarshal(w.Body.Bytes(), &stats)
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &stats))
 	assert.Len(t, stats, 1)
 	assert.Equal(t, 3, stats[0].RequestCount)