docs: add comprehensive K6 load testing guide with API structure

- Document all API endpoints (auth, listings, payments, search)
- Include DTOs and request/response body shapes
- Document authentication methods and rate limits
- Provide database and environment configuration
- Include existing test setup (Playwright, Vitest)
- Detail CI/CD pipeline structure
- Recommend K6 endpoints and test patterns
- Provide file location references for quick lookup

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/web/i18n/navigation.ts

@@ -0,0 +1,4 @@
+import { createNavigation } from 'next-intl/navigation';
+import { routing } from './routing';
+
+export const { Link, redirect, usePathname, useRouter } = createNavigation(routing);