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/plugin.go

@@ -5,13 +5,6 @@
 package upload
 
 import (
-	"context"
-	"embed"
-	"reflect"
-
-	"github.com/gin-gonic/gin"
-	"github.com/hibiken/asynq"
-
 	"Wavelet/core"
 	"Wavelet/core/contracts"
 	"Wavelet/core/extpoints"
@@ -19,6 +12,12 @@ import (
 	"Wavelet/plugins/domain/upload/handler"
 	"Wavelet/plugins/domain/upload/shared"
 	"Wavelet/plugins/domain/upload/task"
+	"context"
+	"embed"
+	"reflect"
+
+	"github.com/gin-gonic/gin"
+	"github.com/hibiken/asynq"
 )
 
 //go:embed migrations/*/*.sql