feat: Reinitialize frontend with SvelteKit and TypeScript

- Delete old Vite+Svelte frontend
- Initialize new SvelteKit project with TypeScript
- Configure Tailwind CSS v4 + DaisyUI
- Implement JWT authentication with auto-refresh
- Create login page with form validation (Zod)
- Add protected route guards
- Update Docker configuration for single-stage build
- Add E2E tests with Playwright (6/11 passing)
- Fix Svelte 5 reactivity with $state() runes

Known issues:
- 5 E2E tests failing (timing/async issues)
- Token refresh implementation needs debugging
- Validation error display timing

backend/.gitattributes

@@ -0,0 +1,11 @@
+* text=auto eol=lf
+
+*.blade.php diff=html
+*.css diff=css
+*.html diff=html
+*.md diff=markdown
+*.php diff=php
+
+/.github export-ignore
+CHANGELOG.md export-ignore
+.styleci.yml export-ignore