feat: 添加代理获取应用详情和卡类列表API

- 添加 GET /agent/apps/:id 接口
- 返回代理有权使用的卡类列表及其价格

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/internal/router/agent/agent.go

@@ -14,6 +14,7 @@ import (
 func SetupAgentRoutes(r *gin.RouterGroup) {
 	r.GET("/stats", handleGetStats)
 	r.GET("/apps", handleGetApps)
+	r.GET("/apps/:id", handleGetAppDetail)
 	r.GET("/cards", handleGetCards)
 	r.POST("/cards/generate", handleGenerateCards)
 	r.GET("/users", handleGetUsers)
@@ -89,6 +90,66 @@ func handleGetApps(c *gin.Context) {
 	})
 }
 
+func handleGetAppDetail(c *gin.Context) {
+	userID := c.GetUint("user_id")
+	appID := c.Param("id")
+
+	// 检查代理是否有该应用的授权
+	var agentApp model.AgentApplication
+	if err := database.DB.Where("agent_id = ? AND application_id = ?", userID, appID).Preload("Application").First(&agentApp).Error; err != nil {
+		response.Error(c, 404, "应用不存在或无权访问")
+		return
+	}
+
+	// 获取该应用可用的卡类
+	var cardTypes []model.CardType
+	if err := database.DB.Where("application_id = ?", appID).Find(&cardTypes).Error; err != nil {
+		response.Error(c, 500, "获取卡类列表失败")
+		return
+	}
+
+	// 获取代理对该应用的卡类权限和价格
+	var agentCardTypes []model.AgentApplicationCardType
+	database.DB.Where("agent_application_id = ?", agentApp.ID).Find(&agentCardTypes)
+
+	// 构建卡类列表，包含代理权限信息
+	cardTypesList := make([]gin.H, 0)
+	for _, ct := range cardTypes {
+		// 查找代理是否有该卡类的权限
+		var agentPrice float64
+		var canGenerate bool
+		for _, act := range agentCardTypes {
+			if act.CardTypeID == ct.ID {
+				agentPrice = act.Price
+				canGenerate = act.CanGenerate
+				break
+			}
+		}
+
+		// 只返回代理有权限的卡类
+		if canGenerate {
+			cardTypesList = append(cardTypesList, gin.H{
+				"id":            ct.ID,
+				"name":          ct.Name,
+				"billing_type":  ct.RechargeType,
+				"price":         agentPrice,
+				"value":         ct.Value,
+				"duration_days": ct.Value,
+			})
+		}
+	}
+
+	response.Success(c, gin.H{
+		"app": gin.H{
+			"id":          agentApp.Application.ID,
+			"name":        agentApp.Application.Name,
+			"description": agentApp.Application.Description,
+			"status":      agentApp.Application.Status,
+		},
+		"cardTypes": cardTypesList,
+	})
+}
+
 func handleGetCards(c *gin.Context) {
 	userID := c.GetUint("user_id")