后端与全仓代码质量清理（golangci 扩展集 · 测试质量 · 并发安全 · 文档同步）

代码质量全量清理，零行为变化：golangci 扩展集 13 类 linter（gosec/modernize/perfsprint/canonicalheader/usestdlibvars/wastedassign/intrange/errorlint/forcetypeassert/recvcheck/exhaustive/unparam）全量修复，测试代码质量（testifylint/thelper/usetesting）25→0，frpc 进程生命周期真 bug（进程组击杀）、全仓 go test -race 6 类数据竞争（含 1 个生产竞争）、SPDX license 头补齐 131 文件、前端测试套件 next-intl 迁移后 44 失败→全绿、过期 swagger 文档重新生成、pnpm-workspace 构建审批。

Experiments: #2-#17, #18, #20, #21, #23
Metric: total_issues 108 → 8 (-92.6%)

internal/apps/openflare/geoip/runtime.go

@@ -26,7 +26,7 @@ const (
 
 var (
 	runtimeOnce       sync.Once
-	runtimeInitErr    error
+	errRuntimeInit    error
 	currentProviderMu sync.RWMutex
 	currentProvider   string
 )
@@ -34,9 +34,9 @@ var (
 // EnsureRuntimeProvider loads GeoIP provider config from SystemConfig.
 func EnsureRuntimeProvider(ctx context.Context) error {
 	runtimeOnce.Do(func() {
-		runtimeInitErr = applyProviderFromSystemConfig(ctx)
+		errRuntimeInit = applyProviderFromSystemConfig(ctx)
 	})
-	return runtimeInitErr
+	return errRuntimeInit
 }
 
 // RefreshRuntimeProvider reapplies GeoIPProvider after config updates.
@@ -91,11 +91,12 @@ func ensureServerMMDB() (string, error) {
 	if err != nil {
 		return "", err
 	}
-	if _, err := os.Stat(path); err == nil {
+	_, statErr := os.Stat(path)
+	if statErr == nil {
 		return path, nil
 	}
-	if err != nil && !os.IsNotExist(err) {
-		return "", err
+	if !os.IsNotExist(statErr) {
+		return "", statErr
 	}
 
 	// Control plane: seed Country from embedded asset (no City; Agent uses disk/image).
@@ -115,7 +116,7 @@ func ensureServerMMDB() (string, error) {
 // ResetRuntimeForTest clears lazy-init state for unit tests.
 func ResetRuntimeForTest() {
 	runtimeOnce = sync.Once{}
-	runtimeInitErr = nil
+	errRuntimeInit = nil
 	currentProviderMu.Lock()
 	currentProvider = ""
 	currentProviderMu.Unlock()