chore: initial snapshot for gitea/github upload

llm-gateway-competitors/sub2api-tar/backend/internal/service/quota_fetcher.go

@@ -0,0 +1,19 @@
+package service
+
+import (
+	"context"
+)
+
+// QuotaFetcher 额度获取接口，各平台实现此接口
+type QuotaFetcher interface {
+	// CanFetch 检查是否可以获取此账户的额度
+	CanFetch(account *Account) bool
+	// FetchQuota 获取账户额度信息
+	FetchQuota(ctx context.Context, account *Account, proxyURL string) (*QuotaResult, error)
+}
+
+// QuotaResult 额度获取结果
+type QuotaResult struct {
+	UsageInfo *UsageInfo     // 转换后的使用信息
+	Raw       map[string]any // 原始响应，可存入 account.Extra
+}