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>

prisma/schema.prisma

@@ -618,18 +618,19 @@ enum SubscriptionStatus {
 }
 
 model Plan {
-  id                  String   @id @default(cuid())
-  tier                PlanTier @unique
-  name                String
-  priceMonthlyVND     BigInt
-  priceYearlyVND      BigInt
-  maxListings         Int?
-  maxSavedSearches    Int?
-  maxAnalyticsQueries Int?
-  maxReports          Int?
-  maxMediaUploads     Int?
-  features            Json
-  isActive            Boolean  @default(true)
+  id                    String   @id @default(cuid())
+  tier                  PlanTier @unique
+  name                  String
+  priceMonthlyVND       BigInt
+  priceYearlyVND        BigInt
+  maxListings           Int?
+  maxSavedSearches      Int?
+  maxAnalyticsQueries   Int?
+  maxReports            Int?
+  maxMediaUploads       Int?
+  featuredListingsQuota Int?
+  features              Json
+  isActive              Boolean  @default(true)
 
   subscriptions Subscription[]
 }
@@ -766,6 +767,8 @@ enum AdminAction {
   LISTING_REJECTED
   LISTING_BULK_APPROVED
   LISTING_BULK_REJECTED
+  LISTING_FEATURED
+  LISTING_UNFEATURED
   USER_BANNED
   USER_UNBANNED
   USER_STATUS_UPDATED