chore(lint): unify formatting on golangci-lint fmt (gofumpt), uncap issue reporting, fix gofumpt drift

- make format 现在与 code-check 使用同一格式化器（golangci-lint fmt），消除 goimports -local 与 gofumpt 的格式拉锯
- .golangci.yml 关闭默认 50/3 截断，完整上报所有问题（只增强不弱化）
- 全库 gofumpt 规范化（203 files, 纯格式无行为变更）

backend/plugins/domain/upload/task/tasks_test.go

@@ -4,6 +4,9 @@
 package task
 
 import (
+	"Wavelet/plugins/domain/upload/filesrv"
+	"Wavelet/plugins/domain/upload/models"
+	"Wavelet/plugins/domain/upload/shared"
 	"bytes"
 	"context"
 	"encoding/json"
@@ -17,10 +20,6 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-
-	"Wavelet/plugins/domain/upload/filesrv"
-	"Wavelet/plugins/domain/upload/models"
-	"Wavelet/plugins/domain/upload/shared"
 )
 
 func TestSystemCleanupHandler_Execute(t *testing.T) {