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/internal/service/stats_buffer_test.go

@@ -7,10 +7,10 @@ import (
 	"testing"
 	"time"
 
+	"nex/backend/internal/domain"
+
 	"github.com/stretchr/testify/assert"
 	"go.uber.org/zap"
-
-	"nex/backend/internal/domain"
 )
 
 type mockStatsRepo struct {
@@ -58,8 +58,10 @@ func TestStatsBuffer_Increment(t *testing.T) {
 
 	var count int64
 	buffer.counters.Range(func(key, value interface{}) bool {
-		counter := value.(*int64)
-		count += atomic.LoadInt64(counter)
+		counter, ok := value.(*int64)
+		if ok {
+			count += atomic.LoadInt64(counter)
+		}
 		return true
 	})
 	assert.Equal(t, int64(3), count)
@@ -82,8 +84,10 @@ func TestStatsBuffer_ConcurrentIncrement(t *testing.T) {
 
 	var count int64
 	buffer.counters.Range(func(key, value interface{}) bool {
-		counter := value.(*int64)
-		count = atomic.LoadInt64(counter)
+		counter, ok := value.(*int64)
+		if ok {
+			count = atomic.LoadInt64(counter)
+		}
 		return true
 	})
 	assert.Equal(t, int64(100), count)
@@ -161,8 +165,10 @@ func TestStatsBuffer_SwapInt64(t *testing.T) {
 
 	var beforeCount int64
 	buffer.counters.Range(func(key, value interface{}) bool {
-		counter := value.(*int64)
-		beforeCount = atomic.LoadInt64(counter)
+		counter, ok := value.(*int64)
+		if ok {
+			beforeCount = atomic.LoadInt64(counter)
+		}
 		return true
 	})
 	assert.Equal(t, int64(2), beforeCount)
@@ -171,8 +177,10 @@ func TestStatsBuffer_SwapInt64(t *testing.T) {
 
 	var afterCount int64
 	buffer.counters.Range(func(key, value interface{}) bool {
-		counter := value.(*int64)
-		afterCount = atomic.LoadInt64(counter)
+		counter, ok := value.(*int64)
+		if ok {
+			afterCount = atomic.LoadInt64(counter)
+		}
 		return true
 	})
 	assert.Equal(t, int64(0), afterCount)
@@ -190,8 +198,10 @@ func TestStatsBuffer_FailRetry(t *testing.T) {
 
 	var count int64
 	buffer.counters.Range(func(key, value interface{}) bool {
-		counter := value.(*int64)
-		count = atomic.LoadInt64(counter)
+		counter, ok := value.(*int64)
+		if ok {
+			count = atomic.LoadInt64(counter)
+		}
 		return true
 	})
 	assert.Equal(t, int64(2), count)