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/tests/TestCase.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace Tests;
+
+use Illuminate\Foundation\Testing\TestCase as BaseTestCase;
+
+abstract class TestCase extends BaseTestCase
+{
+    //
+}