feat: add P0/P1/P2 features + Swagger enrichment for MVP completeness

Closes four gaps the Swagger audit flagged as blocking a full MVP demo,
plus a general documentation pass.

P0 — Forgot/Reset password (auth)
- POST /auth/forgot-password (anti-enumeration: always 200)
- POST /auth/reset-password
- Reuses the Redis-OTP pattern from email/phone change; new key prefix
  auth:password_reset_otp with 15-min TTL.
- Emits PasswordResetRequestedEvent; new listener in notifications
  dispatches the existing password.reset email template (otp +
  expiryMinutes variables already in template.service.ts).
- UserEntity gains changePassword(HashedPassword) domain method; reset
  also revokes all refresh tokens for the user.

P0 — Favorites module
- New SavedListing Prisma model (unique(userId, listingId)) with User
  and Listing back-relations; schema pushed via db push since the
  remote DB was out of sync with migration history.
- New apps/api/src/modules/favorites/ module following the reviews
  module's shape (DDD/CQRS: domain repo + Prisma impl + 2 commands
  + 2 queries + controller).
- POST /favorites/:listingId, DELETE /favorites/:listingId,
  GET /favorites (paginated), GET /favorites/:listingId/check. All
  guarded by JwtAuthGuard.
- FavoritesModule wired into AppModule.

P1 — Resend OTP (auth)
- POST /auth/resend-otp for EMAIL_CHANGE | PHONE_CHANGE. Reads the
  pending OTP payload out of Redis and re-emits the original event
  without minting a new code, so TTL semantics stay intact. Password
  reset resend is done by re-POSTing /auth/forgot-password and is
  deliberately not in this enum.

P1 — Agent self-upgrade (agents)
- POST /agents/me/upgrade lets a BUYER/SELLER convert to AGENT. Creates
  an Agent row (isVerified=false) and flips User.role in one
  $transaction. Rejects if already AGENT/ADMIN or if an Agent row
  already exists.

P2 — Swagger enrichment
- @ApiConsumes('multipart/form-data') + body schema on listings media
  upload.
- GET /subscriptions/quota/:metric now enumerates the real metric
  values from METRIC_TO_PLAN_FIELD.
- POST /avm/batch and /analytics/valuation/batch document the max=50
  batch size from their DTO's @ArrayMaxSize.
- GET /admin/dashboard gains a realistic response example schema.
- Admin-gated endpoints in projects/transfer/industrial gain concrete
  400/401/403/404 responses.

Swagger endpoint count: 170 → 178. Typecheck clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

prisma/schema.prisma

@@ -70,6 +70,7 @@ model User {
   mfaChallenges     MfaChallenge[]
   transferListings  TransferListing[]
   reports           Report[]
+  savedListings     SavedListing[]
 
   @@index([role])
   @@index([kycStatus])
@@ -339,6 +340,7 @@ model Listing {
   inquiries     Inquiry[]
   orders        Order[]
   priceHistories PriceHistory[]
+  savedByUsers  SavedListing[]
 
   // --- Single-column indexes ---
   @@index([status])
@@ -389,6 +391,19 @@ model SavedSearch {
   @@index([userId])
 }
 
+model SavedListing {
+  id        String   @id @default(cuid())
+  userId    String
+  user      User     @relation(fields: [userId], references: [id], onDelete: Cascade)
+  listingId String
+  listing   Listing  @relation(fields: [listingId], references: [id], onDelete: Cascade)
+  createdAt DateTime @default(now())
+
+  @@unique([userId, listingId])
+  @@index([userId, createdAt(sort: Desc)])
+  @@index([listingId])
+}
+
 // =============================================================================
 // TRANSACTIONS
 // =============================================================================