Add ModeTemplate with Svelte 5 frontend and components

- Create reusable components: auth, api-client, shared-types
- ModeTemplate with Hono backend and SvelteKit frontend
- Auth store refactored to class-based Svelte 5 pattern
- SSR-safe hydrate() pattern for localStorage access
- Frontend builds successfully with Svelte 5 runes

ModeTemplate/frontend/.svelte-kit/output/server/entries/pages/callback/_page.svelte.js

@@ -0,0 +1,19 @@
+import "clsx";
+import "@sveltejs/kit/internal";
+import "../../../chunks/exports.js";
+import "../../../chunks/utils.js";
+import "@sveltejs/kit/internal/server";
+import "../../../chunks/state.svelte.js";
+function _page($$renderer, $$props) {
+  $$renderer.component(($$renderer2) => {
+    $$renderer2.push(`<h1>Authenticating...</h1> `);
+    {
+      $$renderer2.push("<!--[!-->");
+      $$renderer2.push(`<p>Please wait...</p>`);
+    }
+    $$renderer2.push(`<!--]-->`);
+  });
+}
+export {
+  _page as default
+};