refactor(config): migrate to SDKConfig and streamline proxy handling

- Replaced `config.Config` with `config.SDKConfig` across components for simpler configuration management.
- Updated proxy setup functions and handlers to align with `SDKConfig` improvements.
- Reorganized handler imports to match new SDK structure.

internal/auth/qwen/qwen_auth.go

@@ -85,7 +85,7 @@ type QwenAuth struct {
 // NewQwenAuth creates a new QwenAuth instance with a proxy-configured HTTP client.
 func NewQwenAuth(cfg *config.Config) *QwenAuth {
 	return &QwenAuth{
-		httpClient: util.SetProxy(cfg, &http.Client{}),
+		httpClient: util.SetProxy(&cfg.SDKConfig, &http.Client{}),
 	}
 }