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>

apps/api/src/modules/auth/presentation/guards/roles.guard.ts

@@ -1,5 +1,5 @@
 import { Injectable, Logger, type CanActivate, type ExecutionContext } from '@nestjs/common';
-import { Reflector } from '@nestjs/core';
+import { type Reflector } from '@nestjs/core';
 import { type UserRole } from '@prisma/client';
 import { ROLES_KEY } from '../decorators/roles.decorator';