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/dom-helpers/cjs/css.d.ts

@@ -0,0 +1,6 @@
+import * as CSS from 'csstype';
+import { CamelProperty, HyphenProperty, Property } from './types';
+declare function style(node: HTMLElement, property: Partial<Record<Property, string>>): void;
+declare function style<T extends HyphenProperty>(node: HTMLElement, property: T): CSS.PropertiesHyphen[T];
+declare function style<T extends CamelProperty>(node: HTMLElement, property: T): CSS.Properties[T];
+export default style;