This PR is presented as a tidy-up but quietly introduces breaking changes that the empty description doesn't call out. Worth either splitting or documenting before merge:

1. Dropped status: 'Success' | 'Failed' from UltraSwapResponseBase — any caller that switches on response.status to distinguish success/failure now silently breaks. If the discriminator is meant to come from elsewhere (e.g. presence of error), the union still works structurally but every existing consumer needs an audit.

2. throw response → throw new UltraSwapApiError(...) — this is a behavioral change at every call site. Existing catch blocks that expect a Response (and call .json() on it, or check .status) will fail. Better error handling is a real improvement, but it has to land with the call-site updates in the same PR, otherwise quotes/swaps will throw uncaught.

3. _fetchAndCheck returns Promise<any> — erases the type safety that the original explicit response.json() calls were leaning on. Worth making it generic: private async _fetchAndCheck<T>(...): Promise<T>.

4. Title "Update UltraSwapService.ts" + empty body for a 146/-83 line refactor across the service surface — please add a description so reviewers can assess intent vs. scope.

Most of the structural cleanup (UltraSwapApiError, route map rename, JSDoc) looks fine in isolation; the concern is bundling breaking interface changes alongside it without notice.