Recover the pre-extraction caching code (from 7a4e0968~1) into a
standalone module at sources/legacy-caching/. This module bundles
@actions/cache@4.0.5 with the existing patch and adapts the old
caching API to the current CacheService interface.
The cache-service-loader now uses the legacy module by default and
only loads the proprietary vendored module when the license is
accepted. Both paths are wrapped in a LoggingCacheService that
identifies which module is active in logs and the Job Summary.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>