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/cache/access_cache.go

@@ -5,13 +5,13 @@
 package cache
 
 import (
+	"Wavelet/plugins/domain/upload/shared"
 	"context"
 	"encoding/json"
 	"strings"
 	"sync"
 	"time"
 
-	"Wavelet/plugins/domain/upload/shared"
 	uploadstorage "Wavelet/plugins/domain/upload/storage"
 )