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/main.ts

@@ -1,9 +1,9 @@
-import { NestFactory } from '@nestjs/core';
 import { ValidationPipe } from '@nestjs/common';
+import { NestFactory } from '@nestjs/core';
 import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
-import { LoggerService, validateEnv } from '@modules/shared';
 import cookieParser from 'cookie-parser';
 import helmet from 'helmet';
+import { LoggerService, validateEnv } from '@modules/shared';
 import { AppModule } from './app.module';
 
 async function bootstrap() {