feat(antigravity): 从 LoadCodeAssist 复用 TierInfo 提取 plan_type

复用已有 GetTier() 返回的 tier ID（free-tier / g1-pro-tier /
g1-ultra-tier），通过 TierIDToPlanType 映射为 Free / Pro / Ultra，
在 loadProjectIDWithRetry 中顺带提取并写入 credentials.plan_type；
前端增加 Abnormal 异常套餐红色标记。

Made-with: Cursor

backend/internal/pkg/antigravity/client.go

@@ -78,7 +78,9 @@ type UserInfo struct {
 // LoadCodeAssistRequest loadCodeAssist 请求
 type LoadCodeAssistRequest struct {
 	Metadata struct {
-		IDEType string `json:"ideType"`
+		IDEType    string `json:"ideType"`
+		IDEVersion string `json:"ideVersion"`
+		IDEName    string `json:"ideName"`
 	} `json:"metadata"`
 }
 
@@ -223,6 +225,23 @@ func (r *LoadCodeAssistResponse) GetAvailableCredits() []AvailableCredit {
 	return r.PaidTier.AvailableCredits
 }
 
+// TierIDToPlanType 将 tier ID 映射为用户可见的套餐名。
+func TierIDToPlanType(tierID string) string {
+	switch strings.ToLower(strings.TrimSpace(tierID)) {
+	case "free-tier":
+		return "Free"
+	case "g1-pro-tier":
+		return "Pro"
+	case "g1-ultra-tier":
+		return "Ultra"
+	default:
+		if tierID == "" {
+			return "Free"
+		}
+		return tierID
+	}
+}
+
 // Client Antigravity API 客户端
 type Client struct {
 	httpClient *http.Client
@@ -421,6 +440,8 @@ func (c *Client) GetUserInfo(ctx context.Context, accessToken string) (*UserInfo
 func (c *Client) LoadCodeAssist(ctx context.Context, accessToken string) (*LoadCodeAssistResponse, map[string]any, error) {
 	reqBody := LoadCodeAssistRequest{}
 	reqBody.Metadata.IDEType = "ANTIGRAVITY"
+	reqBody.Metadata.IDEVersion = "1.20.6"
+	reqBody.Metadata.IDEName = "antigravity"
 
 	bodyBytes, err := json.Marshal(reqBody)
 	if err != nil {