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/web/lib/auth-store.ts

@@ -1,6 +1,6 @@
 import { create } from 'zustand';
-import { authApi, type UserProfile, type LoginPayload, type RegisterPayload } from './auth-api';
 import { ApiError } from './api-client';
+import { authApi, type UserProfile, type LoginPayload, type RegisterPayload } from './auth-api';
 
 function hasAuthCookie(): boolean {
   if (typeof document === 'undefined') return false;