feat!: 账号池改渠道网关,对外协议换成 vivid /v1

- 新增 channels/channel_models:上游 URL + AES-GCM 加密 key +
  并发/权重/本地统计,模型经渠道 /v1/models 导入绑定
- internal/upstream:vivid 协议客户端(NDJSON 流 + jobId 断流重连 +
  uploads 预签名 + models + balance + 错误分类)
- service/v1 重写:权重分组调度、Redis 并发槽 conc:c:、故障转移,
  站内/测试/对外统一走渠道执行器
- 对外端点换成 vivid 四件套:POST /v1/generate(NDJSON+jobId 重连)、
  POST /v1/uploads(SigV4 预签名 PUT)、GET /v1/models、GET /v1/balance,
  错误包 {"error":{"code","message"}}
- API key 新发改 vk_+48hex;删除全部内置 provider 与 token 池
- 管理端:渠道 CRUD/拉模型/导入/余额端点,前端账号页换渠道页,
  概览/文档/测试弹窗适配

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

backend/internal/repo/event_repo.go

@@ -24,8 +24,8 @@ type EventListFilter struct {
 	UserID        string
 	UserIDs       []string // when set, keep ONLY rows whose user_id is in this list (admin 用户搜索)
 	Query         string   // free-text search over prompt / model / error (server-side, 跨页)
-	ExcludeSource string // when set, omit rows with this source (e.g. hide API-key "v1" usage from the customer logs page)
-	Source        string // when set, keep ONLY rows with this source (admin 来源 filter): "v1" (API key) / "user" (前台) / "admin" (测试模型)
+	ExcludeSource string   // when set, omit rows with this source (e.g. hide API-key "v1" usage from the customer logs page)
+	Source        string   // when set, keep ONLY rows with this source (admin 来源 filter): "v1" (API key) / "user" (前台) / "admin" (测试模型)
 	HasFile       bool     // when true, keep ONLY rows with a non-empty file (the 创作记录 gallery — paginates over real media)
 	ExcludeFiles  []string // when set, omit rows whose file is in this list (e.g. hide homepage showcase media from user galleries)
 	MediaOnly     bool     // when true, keep only rows that are pending or have a stored file — the 画图台 grid, so deleted works don't eat a slot
@@ -618,9 +618,16 @@ func (r *EventRepository) MarkRefunded(ctx context.Context, eventID string) (boo
 	return res.RowsAffected == 1, nil
 }
 
-// SetAccount stamps which provider account is fulfilling an in-flight event.
-// Called when generation commits to a token, so the accounts view can count
-// pending events per account and an abandoned-event purge can attribute back.
+// SetUpstreamJob records the job id the upstream assigned (NDJSON jobId frame)
+// for cross-instance debugging. Best-effort.
+func (r *EventRepository) SetUpstreamJob(ctx context.Context, eventID, jobID string) error {
+	return r.db.WithContext(ctx).
+		Model(&model.EventLog{}).
+		Where("id = ?", eventID).
+		Update("upstream_job", jobID).Error
+}
+
+// SetAccount stamps which channel is fulfilling an in-flight event.
 func (r *EventRepository) SetAccount(ctx context.Context, eventID, accountID, accountEmail string) error {
 	return r.db.WithContext(ctx).
 		Model(&model.EventLog{}).