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/dayjs/esm/plugin/updateLocale/index.d.ts

@@ -0,0 +1,8 @@
+import { PluginFunc } from 'dayjs/esm'
+
+declare const plugin: PluginFunc
+export = plugin
+
+declare module 'dayjs/esm' {
+  export function updateLocale(localeName: string, customConfig: Record<string, unknown>): Record<string, unknown>
+}

frontend/node_modules/dayjs/esm/plugin/updateLocale/index.js

@@ -0,0 +1,12 @@
+export default (function (option, Dayjs, dayjs) {
+  dayjs.updateLocale = function (locale, customConfig) {
+    var localeList = dayjs.Ls;
+    var localeConfig = localeList[locale];
+    if (!localeConfig) return;
+    var customConfigKeys = customConfig ? Object.keys(customConfig) : [];
+    customConfigKeys.forEach(function (c) {
+      localeConfig[c] = customConfig[c];
+    });
+    return localeConfig; // eslint-disable-line consistent-return
+  };
+});