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

frontend/tests/setup.ts

@@ -0,0 +1,44 @@
+import { vi } from 'vitest';
+
+// Mock localStorage
+global.localStorage = {
+  getItem: vi.fn(),
+  setItem: vi.fn(),
+  removeItem: vi.fn(),
+  clear: vi.fn(),
+};
+
+// Mock fetch
+global.fetch = vi.fn();
+
+// Mock window
+global.window = {
+  addEventListener: vi.fn(),
+  removeEventListener: vi.fn(),
+  dispatchEvent: vi.fn(),
+  CustomEvent: class CustomEvent {
+    type: string;
+    detail: unknown;
+    constructor(type: string, options?: { detail?: unknown }) {
+      this.type = type;
+      this.detail = options?.detail;
+    }
+  },
+} as unknown as Window & typeof globalThis;
+
+// Mock import.meta.env
+Object.defineProperty(global, 'import', {
+  value: {
+    meta: {
+      env: {
+        VITE_API_URL: 'http://localhost:3000/api',
+      },
+    },
+  },
+  writable: true,
+});
+
+// Cleanup after each test
+afterEach(() => {
+  vi.clearAllMocks();
+});