feat(upstream): custom 模型按媒体分类配置参考文件上限

- ModelConfig 新增 max_reference_videos / max_reference_audios
  (配合既有 max_reference_images);admin 读写接口透传
- custom 模型表单去掉「参考模式」下拉,改为参考图/参考视频/
  参考音频三个数量输入;合计张数走 totalRefLimit 校验
- vivid 上游 /v1/uploads 按文件魔数自动选 kind(image/video/
  audio)与 mime;openai 协议上游遇视频/音频参考自动跳过换号
- videoCaps 让 custom 模型的分类上限在画图台/文档徽标生效
- reference_mode 请求级 override 放行 "media"

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

backend/internal/model/models.go

@@ -95,7 +95,7 @@ type EventLog struct {
 	Duration   string         `gorm:"size:32"`
 	Refs       int            `gorm:"not null;default:0"`
 	DeAI       bool           `gorm:"not null;default:false"` // 去AI特征 was applied (image only)
-	RefFiles   datatypes.JSON `gorm:"type:jsonb"` // relative paths of saved reference images, for回显 on reload
+	RefFiles   datatypes.JSON `gorm:"type:jsonb"`             // relative paths of saved reference images, for回显 on reload
 	Source     string         `gorm:"size:32;index"`
 	// AccountID is the provider token/account chosen to fulfil this generation,
 	// stamped when the upstream call begins. Drives the accounts view's live
@@ -139,7 +139,11 @@ type ModelConfig struct {
 	DurationPricesAgent datatypes.JSONMap `gorm:"type:jsonb;column:duration_prices_agent"`
 	Durations           datatypes.JSON    `gorm:"type:jsonb"`
 	MaxReferenceImages  int               `gorm:"not null;default:0"`
-	ReferenceMode       string            `gorm:"size:32;not null;default:'none'"`
+	// Per-kind reference caps for upstreams that accept video/audio refs
+	// (vivid-protocol custom upstreams). 0 = that kind is not accepted.
+	MaxReferenceVideos int    `gorm:"not null;default:0"`
+	MaxReferenceAudios int    `gorm:"not null;default:0"`
+	ReferenceMode      string `gorm:"size:32;not null;default:'none'"`
 	// Custom-upstream models (provider="custom"): UpstreamModel is the model name
 	// sent to the upstream OpenAI-compatible API; the base_url + key live on the
 	// matching custom account (pool="custom", meta.base_url). Empty for built-ins.
@@ -263,15 +267,15 @@ func AutoMigrateModels() []any {
 type Order struct {
 	ID          string    `gorm:"primaryKey;size:40"`
 	UserID      string    `gorm:"size:32;index;not null"`
-	Amount      float64   `gorm:"not null"`               // 充值金额(元)
-	Points      int       `gorm:"not null"`               // 到账积分
-	PayType     string    `gorm:"size:16"`                // wxpay | alipay | admin | cdk
-	Status      string    `gorm:"size:16;index;not null"` // pending | paid | cancelled
+	Amount      float64   `gorm:"not null"`                              // 充值金额(元)
+	Points      int       `gorm:"not null"`                              // 到账积分
+	PayType     string    `gorm:"size:16"`                               // wxpay | alipay | admin | cdk
+	Status      string    `gorm:"size:16;index;not null"`                // pending | paid | cancelled
 	Source      string    `gorm:"size:16;index;not null;default:'epay'"` // epay | admin | cdk
-	Remark      string    `gorm:"type:text"`              // e.g. 兑换码 code / 管理员操作说明
-	TradeNo     string    `gorm:"size:64;index"`          // 易支付平台订单号
-	PayInfo     string    `gorm:"type:text"`              // 二维码 url / 跳转 url
-	PayInfoType string    `gorm:"size:16"`                // qrcode | jump | html | ...
+	Remark      string    `gorm:"type:text"`                             // e.g. 兑换码 code / 管理员操作说明
+	TradeNo     string    `gorm:"size:64;index"`                         // 易支付平台订单号
+	PayInfo     string    `gorm:"type:text"`                             // 二维码 url / 跳转 url
+	PayInfoType string    `gorm:"size:16"`                               // qrcode | jump | html | ...
 	ExpiresAt   time.Time `gorm:"index"`
 	PaidAt      *time.Time
 	CreatedAt   time.Time
@@ -294,10 +298,10 @@ type ConcurrencyGroup struct {
 // node/edge graph as a versioned JSON blob; saves are whole-document
 // replacements (last write wins), which matches the single-editor frontend.
 type Canvas struct {
-	ID        string    `gorm:"primaryKey;size:40"`
-	UserID    string    `gorm:"size:32;index;not null"`
-	Title     string    `gorm:"size:120;not null;default:'未命名画布'"`
-	Data      string    `gorm:"type:text"`
+	ID        string `gorm:"primaryKey;size:40"`
+	UserID    string `gorm:"size:32;index;not null"`
+	Title     string `gorm:"size:120;not null;default:'未命名画布'"`
+	Data      string `gorm:"type:text"`
 	CreatedAt time.Time
 	UpdatedAt time.Time `gorm:"index"`
 }