feat(antigravity): 添加账户类型（tier）显示功能

backend/internal/pkg/antigravity/client.go

@@ -36,9 +36,30 @@ type LoadCodeAssistRequest struct {
 	} `json:"metadata"`
 }
 
+// TierInfo 账户类型信息
+type TierInfo struct {
+	ID          string `json:"id"`          // standard-tier, free-tier, g1-pro-tier, g1-ultra-tier
+	Name        string `json:"name"`        // 显示名称
+	Description string `json:"description"` // 描述
+}
+
 // LoadCodeAssistResponse loadCodeAssist 响应
 type LoadCodeAssistResponse struct {
-	CloudAICompanionProject string `json:"cloudaicompanionProject"`
+	CloudAICompanionProject string    `json:"cloudaicompanionProject"`
+	CurrentTier             *TierInfo `json:"currentTier,omitempty"`
+	PaidTier                *TierInfo `json:"paidTier,omitempty"`
+}
+
+// GetTier 获取账户类型
+// 优先返回 paidTier（付费订阅级别），否则返回 currentTier
+func (r *LoadCodeAssistResponse) GetTier() string {
+	if r.PaidTier != nil && r.PaidTier.ID != "" {
+		return r.PaidTier.ID
+	}
+	if r.CurrentTier != nil {
+		return r.CurrentTier.ID
+	}
+	return ""
 }
 
 // Client Antigravity API 客户端

backend/internal/service/antigravity_quota_refresher.go

@@ -145,8 +145,15 @@ func (r *AntigravityQuotaRefresher) refreshAccountQuota(ctx context.Context, acc
 		}
 	}
 
-	// 调用 API 获取配额
 	client := antigravity.NewClient(proxyURL)
+
+	// 获取账户类型（tier）
+	loadResp, _ := client.LoadCodeAssist(ctx, accessToken)
+	if loadResp != nil {
+		r.updateAccountTier(account, loadResp)
+	}
+
+	// 调用 API 获取配额
 	modelsResp, err := client.FetchAvailableModels(ctx, accessToken, projectID)
 	if err != nil {
 		return err
@@ -170,6 +177,18 @@ func (r *AntigravityQuotaRefresher) isTokenExpired(account *Account) bool {
 	return time.Now().Add(5 * time.Minute).After(*expiresAt)
 }
 
+// updateAccountTier 更新账户类型信息
+func (r *AntigravityQuotaRefresher) updateAccountTier(account *Account, loadResp *antigravity.LoadCodeAssistResponse) {
+	if account.Extra == nil {
+		account.Extra = make(map[string]any)
+	}
+
+	tier := loadResp.GetTier()
+	if tier != "" {
+		account.Extra["tier"] = tier
+	}
+}
+
 // updateAccountQuota 更新账户的配额信息
 func (r *AntigravityQuotaRefresher) updateAccountQuota(account *Account, modelsResp *antigravity.FetchAvailableModelsResponse) {
 	if account.Extra == nil {