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/claude/anthropic_auth.go

@@ -59,7 +59,7 @@ type ClaudeAuth struct {
 //   - *ClaudeAuth: A new Claude authentication service instance
 func NewClaudeAuth(cfg *config.Config) *ClaudeAuth {
 	return &ClaudeAuth{
-		httpClient: util.SetProxy(cfg, &http.Client{}),
+		httpClient: util.SetProxy(&cfg.SDKConfig, &http.Client{}),
 	}
 }