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/fetch/AbortSignal.d.ts

@@ -0,0 +1,86 @@
+import EventTarget from '../event/EventTarget.js';
+import * as PropertySymbol from '../PropertySymbol.js';
+import Event from '../event/Event.js';
+import BrowserWindow from '../window/BrowserWindow.js';
+/**
+ * AbortSignal.
+ *
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal
+ */
+export default class AbortSignal extends EventTarget {
+    protected static [PropertySymbol.window]: BrowserWindow;
+    protected [PropertySymbol.window]: BrowserWindow;
+    [PropertySymbol.aborted]: boolean;
+    [PropertySymbol.reason]: any;
+    onabort: ((this: AbortSignal, event: Event) => void) | null;
+    /**
+     * Constructor.
+     */
+    constructor();
+    /**
+     * Return a default description for the AbortSignal class.
+     */
+    get [Symbol.toStringTag](): string;
+    /**
+     * Returns true if the signal has been aborted.
+     *
+     * @returns True if the signal has been aborted.
+     */
+    get aborted(): boolean;
+    /**
+     * Setter for aborted. Value will be ignored as the property is read-only.
+     *
+     * @param _value Aborted.
+     */
+    set aborted(_value: boolean);
+    /**
+     * Returns the reason the signal was aborted.
+     *
+     * @returns Reason.
+     */
+    get reason(): any;
+    /**
+     * Setter for reason. Value will be ignored as the property is read-only.
+     *
+     * @param _value Reason.
+     */
+    set reason(_value: any);
+    /**
+     * Aborts the signal.
+     *
+     * @param [reason] Reason.
+     */
+    [PropertySymbol.abort](reason?: any): void;
+    /**
+     * Throws an "AbortError" if the signal has been aborted.
+     */
+    throwIfAborted(): void;
+    /**
+     * Returns an AbortSignal instance that has been set as aborted.
+     *
+     * @param [reason] Reason.
+     * @returns AbortSignal instance.
+     */
+    static abort(reason?: any): AbortSignal;
+    /**
+     * Returns an AbortSignal that will automatically abort after a specified
+     * time.
+     *
+     * @param [time] Time in milliseconds.
+     * @returns AbortSignal instance.
+     */
+    static timeout(time: number): AbortSignal;
+    /**
+     * Takes an iterable of abort signals and returns an AbortSignal that is
+     * aborted when any of the input iterable abort signals are aborted.
+     *
+     * The abort reason will be set to the reason of the first signal that is
+     * aborted. If any of the given abort signals are already aborted then so will
+     * be the returned AbortSignal.
+     *
+     * @param [signals] Iterable of abort signals.
+     * @returns AbortSignal instance.
+     */
+    static any(signals: AbortSignal[]): AbortSignal;
+}
+//# sourceMappingURL=AbortSignal.d.ts.map