feat(listings): R2.3 featured listings entitlement + admin promote + search filter (TEC-2754)
- Add Plan.featuredListingsQuota (Int?) with per-tier seed (FREE=0, AGENT_PRO=5, INVESTOR=10, ENTERPRISE unlimited) and migration 20260418000000_add_featured_listings_quota
- Wire featured_listings_promoted metric into CheckQuotaHandler METRIC_TO_PLAN_FIELD so QuotaGuard honors the new quota
- Add PromoteFeaturedListingCommand + handler (entitlement-based, no payment): verifies ownership/agent, checks quota, extends featuredUntil, meters usage
- Add POST /listings/:id/promote endpoint gated by @RequireQuota('featured_listings_promoted') + QuotaGuard
- Add AdminFeatureListingCommand + handler with LISTING_FEATURED / LISTING_UNFEATURED audit log entries (new AdminAction enum values) and transactional write
- Add POST /admin/moderation/listings/:id/feature endpoint (ADMIN-only) with reason + duration
- Expose featured?: boolean filter on SearchPropertiesDto -> isFeatured:=1|0 Typesense filter in SearchPropertiesHandler
- Unit tests: 8 for PromoteFeaturedListingHandler, 6 for AdminFeatureListingHandler, 3 for search featured filter
Keeps existing pay-per-feature FeatureListingHandler intact for backward compatibility.
Co-Authored-By: Paperclip <noreply@paperclip.ing>