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/node_modules/happy-dom/lib/nodes/html-input-element/HTMLInputElementValueStepping.d.ts

@@ -0,0 +1,16 @@
+/**
+ * HTML input element value stepping.
+ */
+export default class HTMLInputElementValueStepping {
+    /**
+     * Steps up or down.
+     *
+     * @param type Type.
+     * @param value Value.
+     * @param direction Direction.
+     * @param [increment] Increment.
+     * @returns New value.
+     */
+    static step(type: string, value: string, direction: -1 | 1, increment?: number): string;
+}
+//# sourceMappingURL=HTMLInputElementValueStepping.d.ts.map