模型限制: 系统配置全局开放/禁止 + 用户级限制 + 网关拦截

- User 新增 allowed_models/denied_models(用户级模型限制)
- 系统配置 model_allowlist/model_denylist 全局策略, 保存即时失效网关缓存
- 网关 checkModelAllowed: 用户级 > 全局(禁止命中→403, 白名单非空→仅白名单)
- 三个协议处理器均校验, 错误按客户端协议格式返回
- 配置页"模型限制"卡片(全局允许/禁止多选); 用户编辑支持允许/禁止模型

Co-Authored-By: Claude <noreply@anthropic.com>

server/internal/api/auth.go

@@ -8,18 +8,20 @@ import (
 	"time"
 
 	"github.com/gin-gonic/gin"
-	"github.com/openteam/server/internal/app"
 	"github.com/openteam/server/internal/api/middleware"
+	"github.com/openteam/server/internal/app"
 	"github.com/openteam/server/internal/pkg/resp"
+	"github.com/openteam/server/internal/proxy"
 	"github.com/openteam/server/internal/store"
 )
 
 // Handler 聚合所有管理 API。
 type Handler struct {
-	a *app.App
+	a  *app.App
+	gw *proxy.Gateway
 }
 
-func NewHandler(a *app.App) *Handler { return &Handler{a: a} }
+func NewHandler(a *app.App, gw *proxy.Gateway) *Handler { return &Handler{a: a, gw: gw} }
 
 // ---------------------------------------------------------------------------
 // 认证
@@ -219,6 +221,8 @@ func (h *Handler) publicUser(u *store.User) gin.H {
 		"role":       u.Role,
 		"balance":    u.Balance,
 		"status":     u.Status,
+		"allowed_models": u.AllowedModels,
+		"denied_models":  u.DeniedModels,
 		"created_at": u.CreatedAt,
 	}
 }