- Remove CacheCheckResult and simplify Cache::check_cache to return
Option<OrganizationPlan>
- Replace cache_response_with_metadata with cache_response that takes a
base path; update Gemini client and tests to use new API
- Improve load_or_create error handling and early-return when cache file
missing
- Expand README/docs/INSTALLATION.md with detailed per-OS install and
PATH instructions