fix(utils): trim trailing whitespace from base URLs (resolves #530)

[crayonlu]

Fixes a bug where baseURL values that include trailing control/whitespace characters (e.g., \r) caused incorrect URL merging (the path was dropped and only query params remained). This change trims trailing whitespace from the provided base before joining paths and adds a regression test.

ofetch('/path', {
  baseURL: 'https://example.org/\r',
  query: { q: 'y' },
  onRequest: [({ request }) => console.log(request.toString())]
});

// wrong: https://example.org/?q=y
// expect: https://example.org/path?q=y