Bug: Silent failures when creating token storage directory

[mango766]

I noticed in src/token_storage.rs that failures to create the token directory or set its permissions are silently ignored using let _.\n\nrust\nlet _ = tokio::fs::create_dir_all(parent).await;\n// ...\nlet _ = std::fs::set_permissions(parent, std::fs::Permissions::from_mode(0o700));\n\n\nIf directory creation fails (e.g. due to permissions), the subsequent file write will likely fail with a confusing error, or if permission setting fails, the token file might be left with insecure permissions.\n\nThese errors should probably be propagated up to the caller.