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/cmd/marklabel/main.go

@@ -1,45 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"os"
-
-	"gorm.io/driver/postgres"
-	"gorm.io/gorm"
-)
-
-type row struct {
-	ID           string
-	Pool         string
-	Status       string
-	AccountEmail string
-	ImageLimited bool
-	VideoLimited bool
-}
-
-func main() {
-	dsn := os.Getenv("POSTGRES_DSN")
-	if dsn == "" {
-		fmt.Println("POSTGRES_DSN env is required, e.g. host=127.0.0.1 user=postgres password=... dbname=vivid_ai port=5432 sslmode=disable TimeZone=Asia/Shanghai")
-		os.Exit(1)
-	}
-	db, err := gorm.Open(postgres.Open(dsn), &gorm.Config{})
-	if err != nil {
-		fmt.Println("open err:", err)
-		os.Exit(1)
-	}
-
-	var pick row
-	db.Raw(`SELECT id, pool, status, account_email, image_limited, video_limited FROM token_accounts WHERE pool='adobe' ORDER BY id LIMIT 1`).Scan(&pick)
-	fmt.Printf("picked: id=%s email=%s status=%s image_limited=%v video_limited=%v\n", pick.ID, pick.AccountEmail, pick.Status, pick.ImageLimited, pick.VideoLimited)
-
-	if err := db.Exec(`UPDATE token_accounts SET video_limited=true, updated_at=now() WHERE id=?`, pick.ID).Error; err != nil {
-		fmt.Println("update err:", err)
-		os.Exit(1)
-	}
-	fmt.Println("-> set video_limited=true")
-
-	var after row
-	db.Raw(`SELECT id, pool, status, account_email, image_limited, video_limited FROM token_accounts WHERE id=?`, pick.ID).Scan(&after)
-	fmt.Printf("after:  id=%s status=%s image_limited=%v video_limited=%v\n", after.ID, after.Status, after.ImageLimited, after.VideoLimited)
-}