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%)

scripts/live_ch_smoke/main.go

@@ -1,3 +1,6 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
 // Package main is a manual smoke tool for ClickHouse app write path.
 // Usage (from repo root, with config.yaml and Docker CH up):
 //
@@ -6,6 +9,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"time"
@@ -32,7 +36,7 @@ func main() {
 
 func run() error {
 	if !db.ChConnReady() {
-		return fmt.Errorf("ChConn not ready — check config.yaml clickhouse.enabled")
+		return errors.New("ChConn not ready — check config.yaml clickhouse.enabled")
 	}
 	ctx := context.Background()
 	chwriter.Init(ctx)
@@ -76,7 +80,7 @@ func waitForSnapshot(ctx context.Context, nodeID string, now time.Time) error {
 		}
 		time.Sleep(pollInterval)
 	}
-	return fmt.Errorf("not flushed within timeout")
+	return errors.New("not flushed within timeout")
 }
 
 func assertLatestIncludes(ctx context.Context, nodeID string, now time.Time) error {