feat: add authHeader field to OpenClawProviderConfig and reuse type in form state

Add optional `authHeader` boolean to support vendor-specific auth headers
(e.g. Longcat). Refactor `resetOpenclawState` to use the shared
`OpenClawProviderConfig` type instead of an inline duplicate definition.

src/types.ts

@@ -523,6 +523,7 @@ export interface OpenClawProviderConfig {
   api?: string; // API 协议类型（如 "openai-completions"、"anthropic"）
   models?: OpenClawModel[]; // 可用模型列表
   headers?: Record<string, string>; // 自定义请求头（如 User-Agent）
+  authHeader?: boolean; // 供应商自定义认证开关（如 Longcat）
 }
 
 // OpenClaw agents.defaults 完整配置