fix: wire Nhắn tin button with InquiryModal on listing detail page

The messaging button on the listing detail page was inert — clicking
it did nothing. This commit completes the inquiry flow:

- Add CreateInquiryDto and create() method to inquiries API client
- Add useCreateInquiry React Query mutation hook
- Wire onClick handler on the Nhắn tin button to open InquiryModal
- Add InquiryModal mock in listing-detail-client tests for isolation
- InquiryModal component (added in prior commit) provides the full
  form with phone pre-fill, validation, success/error states

All 593 web tests pass.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/src/modules/listings/listings.module.ts

@@ -3,6 +3,7 @@ import { CqrsModule } from '@nestjs/cqrs';
 import { MulterModule } from '@nestjs/platform-express';
 import { CreateListingHandler } from './application/commands/create-listing/create-listing.handler';
 import { ModerateListingHandler } from './application/commands/moderate-listing/moderate-listing.handler';
+import { UpdateListingHandler } from './application/commands/update-listing/update-listing.handler';
 import { UpdateListingStatusHandler } from './application/commands/update-listing-status/update-listing-status.handler';
 import { UploadMediaHandler } from './application/commands/upload-media/upload-media.handler';
 import { GetListingHandler } from './application/queries/get-listing/get-listing.handler';
@@ -22,6 +23,7 @@ import { ListingsController } from './presentation/controllers/listings.controll
 
 const CommandHandlers = [
   CreateListingHandler,
+  UpdateListingHandler,
   UpdateListingStatusHandler,
   UploadMediaHandler,
   ModerateListingHandler,