feat(provider): 新增 OpenRouter 平台适配器 - GET /api/v1/credits，Bearer 认证 - 余额 = data.total_credits - data.total_usage（剩余可用） - 重启后自动同步为平台记录

app/providers/__init__.py

@@ -4,9 +4,11 @@ from __future__ import annotations
 
 from app.providers.base import BalanceProvider
 from app.providers.deepseek import DeepSeekProvider
+from app.providers.openrouter import OpenRouterProvider
 
 PROVIDERS: dict[str, type[BalanceProvider]] = {
     "deepseek": DeepSeekProvider,
+    "openrouter": OpenRouterProvider,
 }