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/app/(dashboard)/dashboard/page.tsx

@@ -1,18 +1,8 @@
 'use client';
 
-import { useEffect, useState } from 'react';
 import Image from 'next/image';
 import Link from 'next/link';
-import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
-import { Button } from '@/components/ui/button';
-import { Badge } from '@/components/ui/badge';
-import { ListingStatusBadge } from '@/components/listings/listing-status-badge';
-import {
-  analyticsApi,
-  type MarketReportDistrict,
-  type HeatmapDataPoint,
-} from '@/lib/analytics-api';
-import { listingsApi, type ListingDetail, type PaginatedResult } from '@/lib/listings-api';
+import { useEffect, useState } from 'react';
 import {
   BarChart,
   Bar,
@@ -22,6 +12,15 @@ import {
   Tooltip,
   ResponsiveContainer,
 } from 'recharts';
+import { ListingStatusBadge } from '@/components/listings/listing-status-badge';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
+import {
+  analyticsApi,
+  type MarketReportDistrict,
+  type HeatmapDataPoint,
+} from '@/lib/analytics-api';
+import { listingsApi, type ListingDetail, type PaginatedResult } from '@/lib/listings-api';
 
 const CITY = 'Ho Chi Minh';
 const PERIOD = '2026-Q1';