refactor(archive): remove archive on provider switches/updates

- Remove file archiving when switching providers or updating current provider
- Keep archive functionality only for initial migration (one-time operation)
- Retain simple .bak backup for config.json on each save
- Simplify code by removing unnecessary archive operations from daily workflows

This change prevents unlimited archive growth while maintaining data safety through:
1. Initial migration archives for historical data preservation
2. Single .bak file for basic rollback capability
3. All provider configs stored in SSOT (config.json)

src-tauri/src/config.rs

@@ -88,6 +88,7 @@ pub fn archive_file(ts: u64, category: &str, src: &Path) -> Result<Option<PathBu
     Ok(Some(dest))
 }
 
+
 /// 清理供应商名称，确保文件名安全
 pub fn sanitize_provider_name(name: &str) -> String {
     name.chars()