docs: document extract-test-cache.sh and cache key behavior (!169) · Merge requests · hive / Common CI Configuration · GitLab

Summary

Document the new .fetch_extract_test_cache template added in !168 (merged)
Document the extract-test-cache.sh script's environment variables and features
Add note about exact cache key matching (no fallback to different app versions)
Clarify schema compatibility guarantees

This documentation accompanies the changes from:

!167 (merged) (remove smart cache fallback)
!168 (merged) (add shared extract-test-cache.sh script)