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/agent/runtimeuser/runtimeuser.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 // Package runtimeuser defines the shared OS account used by the agent process
 // and OpenResty worker processes so file ownership stays aligned.
 package runtimeuser
@@ -120,7 +123,7 @@ func ensureWorldTraversablePath(targetDir string) error {
 	if current == "" || current == "." {
 		return nil
 	}
-	for depth := 0; depth < maxDepth; depth++ {
+	for range maxDepth {
 		if err := os.Chmod(current, DefaultDirPerm); err != nil { //nolint:gosec // parent dirs must be traversable by the runtime user
 			if os.IsNotExist(err) || os.IsPermission(err) {
 				break

internal/apps/agent/runtimeuser/runtimeuser_test.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package runtimeuser
 
 import (

internal/apps/agent/runtimeuser/runtimeuser_unix.go

@@ -1,5 +1,8 @@
 //go:build unix
 
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 package runtimeuser
 
 import (