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/uptimekuma/sync_helpers.go

@@ -5,6 +5,7 @@ package uptimekuma
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log/slog"
 	"strings"
@@ -18,13 +19,13 @@ const monitorListWaitTimeout = 5 * time.Second
 // validateKumaConfig 验证 kumaConfig 配置完整性
 func validateKumaConfig(config *kumaConfig) error {
 	if strings.TrimSpace(config.URL) == "" {
-		return fmt.Errorf("uptime Kuma URL is not configured")
+		return errors.New("uptime Kuma URL is not configured")
 	}
 	if strings.TrimSpace(config.Username) == "" {
-		return fmt.Errorf("uptime Kuma username is not configured")
+		return errors.New("uptime Kuma username is not configured")
 	}
 	if strings.TrimSpace(config.Password) == "" {
-		return fmt.Errorf("uptime Kuma password is not configured")
+		return errors.New("uptime Kuma password is not configured")
 	}
 	return nil
 }
@@ -65,7 +66,7 @@ func connectAndLoginUptimeKuma(kumaURL, kumaUsername, kumaPassword string) (*Soc
 	case <-time.After(monitorListWaitTimeout):
 		client.Close()
 		slog.Error("Timeout waiting for Uptime Kuma monitorList push event")
-		return nil, fmt.Errorf("timeout waiting for monitorList event from Uptime Kuma")
+		return nil, errors.New("timeout waiting for monitorList event from Uptime Kuma")
 	}
 	return client, nil
 }