trud 0.2.1

Bug fixes

Fixed download failure for items with spaces in archive filenames by URL-encoding the download URL (#7).

Enhanced parameter design with enum validation:
- get_item_metadata() and get_subscribed_metadata() now use release_scope = c("all", "latest") parameter instead of latest_only boolean. This makes function calls more expressive and eliminates boolean ambiguity.
- download_item() now uses file_type = c("archive", "checksum", "signature", "publicKey") parameter instead of download_file.
Added overwrite parameter to download_item() allowing users to explicitly control whether existing files should be overwritten.
Breaking changes:
- Removed TRUD_API_KEY parameter from all exported functions. API keys must now be set via the TRUD_API_KEY environment variable only.
- download_item() parameter download_file renamed to file_type with enhanced validation.
- get_item_metadata() and get_subscribed_metadata() parameter latest_only replaced with release_scope.

Improved documentation and user experience:
- Enhanced subscription workflow documentation with clear step-by-step guidance.
- Added explanation that purrr::map_at() pattern is used in examples to avoid exposing API keys.
- Clarified how to obtain and use release IDs from get_item_metadata() for downloading specific releases.
Enhanced robustness and testing:
- Added validation warnings to trud_items() to detect changes in NHS TRUD website structure that might break the scraper.
- Refactored tests to use withr::local_tempdir() for better test isolation and cleanup.
- Improved test descriptions to be more specific and informative.
- Enhanced error handling with better retry logic and rate limiting.
Technical improvements:
- Added support for custom user agent headers via TRUD_USER_AGENT environment variable.
- Improved file existence handling in download_item() with clearer warning messages.
- Enhanced request handling with retry logic, and rate limiting.
- Consistently return file paths invisibly from download_item().