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-element/HTMLElementUtility.js

@@ -0,0 +1,71 @@
+import FocusEvent from '../../event/events/FocusEvent.js';
+import * as PropertySymbol from '../../PropertySymbol.js';
+/**
+ * HTMLElement utility.
+ */
+export default class HTMLElementUtility {
+    /**
+     * Triggers a blur event.
+     *
+     * @param element Element.
+     */
+    static blur(element) {
+        const target = element[PropertySymbol.proxy] || element;
+        const document = target[PropertySymbol.ownerDocument];
+        if (document[PropertySymbol.activeElement] !== target ||
+            !target[PropertySymbol.isConnected] ||
+            target.disabled) {
+            return;
+        }
+        const relatedTarget = document[PropertySymbol.nextActiveElement] ?? null;
+        document[PropertySymbol.activeElement] = null;
+        document[PropertySymbol.clearCache]();
+        target.dispatchEvent(new FocusEvent('blur', {
+            relatedTarget,
+            bubbles: false,
+            composed: true,
+            cancelable: true
+        }));
+        target.dispatchEvent(new FocusEvent('focusout', {
+            relatedTarget,
+            bubbles: true,
+            composed: true,
+            cancelable: true
+        }));
+    }
+    /**
+     * Triggers a focus event.
+     *
+     * @param element Element.
+     */
+    static focus(element) {
+        const target = element[PropertySymbol.proxy] || element;
+        const document = target[PropertySymbol.ownerDocument];
+        if (document[PropertySymbol.activeElement] === target ||
+            !target[PropertySymbol.isConnected] ||
+            target.disabled) {
+            return;
+        }
+        // Set the next active element so `blur` can use it for `relatedTarget`.
+        document[PropertySymbol.nextActiveElement] = target;
+        const relatedTarget = document[PropertySymbol.activeElement];
+        if (document[PropertySymbol.activeElement] !== null) {
+            document[PropertySymbol.activeElement].blur();
+        }
+        // Clean up after blur, so it does not affect next blur call.
+        document[PropertySymbol.nextActiveElement] = null;
+        document[PropertySymbol.activeElement] = target;
+        document[PropertySymbol.clearCache]();
+        target.dispatchEvent(new FocusEvent('focus', {
+            relatedTarget,
+            bubbles: false,
+            composed: true
+        }));
+        target.dispatchEvent(new FocusEvent('focusin', {
+            relatedTarget,
+            bubbles: true,
+            composed: true
+        }));
+    }
+}
+//# sourceMappingURL=HTMLElementUtility.js.map