fix: production readiness — resolve build, lint, and code quality issues

- Fix Next.js build failure: remove duplicate route at (dashboard)/listings/[id]
  that conflicted with (public)/listings/[id] (same URL path in two route groups)
- Fix 772 ESLint errors: auto-fix import ordering (import-x/order), remove unused
  imports/variables, convert empty interfaces to type aliases, replace require()
  with ESM imports, fix consistent-type-imports violations
- Add CLAUDE.md for developer onboarding documentation
- All checks pass: 0 lint errors, typecheck clean, 230 tests passing, build success

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

prisma/seed.ts

@@ -6,9 +6,9 @@ import {
   ListingStatus,
   Direction,
 } from '@prisma/client';
-import { PLANS, seedPlans } from '../scripts/seed-plans';
-import { HCM_DISTRICTS, HANOI_DISTRICTS, DANANG_DISTRICTS, CITY_COORDINATES } from '../scripts/seed-districts';
 import { importMarketData } from '../scripts/import-market-data';
+import { HCM_DISTRICTS, HANOI_DISTRICTS, DANANG_DISTRICTS, CITY_COORDINATES } from '../scripts/seed-districts';
+import { PLANS, seedPlans } from '../scripts/seed-plans';
 
 const prisma = new PrismaClient();