- Create @Cacheable method decorator for declarative cache-aside pattern
with configurable prefix, TTL, resource label, and key extraction
- Add PLAN_LIST (1h TTL) and REFERENCE_DATA (24h TTL) cache constants
- Add CachePrefix.PLAN_LIST and CachePrefix.REFERENCE entries
- Cache subscription plan queries in GetPlanHandler (single + list)
- Export Cacheable decorator from shared module barrel
- Add comprehensive tests for decorator and handler caching
The caching infrastructure (CacheService, Redis, Prometheus metrics,
event-driven invalidation) was already production-ready with 10+ hot
paths cached. This commit adds the missing declarative decorator and
plan list caching.
Resolves: TEC-1567
Co-Authored-By: Paperclip <noreply@paperclip.ing>
2611cfa867