4e7b072f82
Add ChangedFile type and GetChangedFiles() method that calls the Gitea
API endpoint GET /repos/{owner}/{repo}/pulls/{index}/files to retrieve
the list of files changed in a pull request. This is a prerequisite for
displaying changed files in the PR detail view (#189).
Includes unit tests for success and error cases.
Closes leeworks-agents/gitea-mobile#205
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>