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-track-element/HTMLTrackElement.d.ts

@@ -0,0 +1,85 @@
+import HTMLElement from '../html-element/HTMLElement.js';
+import TextTrack from '../html-media-element/TextTrack.js';
+import Event from '../../event/Event.js';
+/**
+ * HTMLTrackElement
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/HTMLTrackElement
+ */
+export default class HTMLTrackElement extends HTMLElement {
+    get oncuechange(): ((event: Event) => void) | null;
+    set oncuechange(value: ((event: Event) => void) | null);
+    /**
+     * Returns kind.
+     *
+     * @returns Kind.
+     */
+    get kind(): string;
+    /**
+     * Sets kind.
+     *
+     * @param value Value.
+     */
+    set kind(value: string);
+    /**
+     * Returns source.
+     *
+     * @returns Source.
+     */
+    get src(): string;
+    /**
+     * Sets source.
+     *
+     * @param src Source.
+     */
+    set src(src: string);
+    /**
+     * Returns source language.
+     *
+     * @returns Source language.
+     */
+    get srclang(): string;
+    /**
+     * Sets source language.
+     *
+     * @param value Value.
+     */
+    set srclang(value: string);
+    /**
+     * Returns label.
+     *
+     * @returns Label.
+     */
+    get label(): string;
+    /**
+     * Sets label.
+     *
+     * @param value Value.
+     */
+    set label(value: string);
+    /**
+     * Returns default.
+     *
+     * @returns Default.
+     */
+    get default(): boolean;
+    /**
+     * Sets default.
+     *
+     * @param value Value.
+     */
+    set default(value: boolean);
+    /**
+     * Returns ready state.
+     *
+     * @returns Ready state.
+     */
+    get readyState(): number;
+    /**
+     * Returns the TextTrack object corresponding to the track element.
+     *
+     * @returns TextTrack
+     */
+    get track(): TextTrack;
+}
+//# sourceMappingURL=HTMLTrackElement.d.ts.map