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/cmd/banner.go

@@ -34,18 +34,18 @@ func formatStartupBanner(state startupState) string {
 		"/ /_/ / /_/ /  __/ / / / __/ / / /_/ / /  /  __/",
 		"\\____/ .___/\\___/_/ /_/_/   /_/\\__,_/_/   \\___/ ",
 		"      /_/                                         ",
-		fmt.Sprintf(" OpenFlare %s", buildinfo.Version),
+		" OpenFlare " + buildinfo.Version,
 		"",
-		fmt.Sprintf(" Environment: %s", config.Config.App.Env),
+		" Environment: " + config.Config.App.Env,
 		fmt.Sprintf(" Runtime:     %s/%s (%s)", runtime.GOOS, runtime.GOARCH, runtime.Version()),
-		fmt.Sprintf(" Build time:  %s", buildTime()),
-		fmt.Sprintf(" Database:    %s", formatMigration(state.relationalDB)),
-		fmt.Sprintf(" Analytics:   %s", formatMigration(state.clickHouseDB)),
+		" Build time:  " + buildTime(),
+		" Database:    " + formatMigration(state.relationalDB),
+		" Analytics:   " + formatMigration(state.clickHouseDB),
 	}
 	if state.listensForHTTP {
-		lines = append(lines, fmt.Sprintf(" Listening:   http://%s", config.Config.App.Addr))
+		lines = append(lines, " Listening:   http://"+config.Config.App.Addr)
 	}
-	lines = append(lines, fmt.Sprintf(" Mode:        %s", state.mode), "")
+	lines = append(lines, " Mode:        "+state.mode, "")
 	return strings.Join(lines, "\n")
 }