Add stage 4: frontend lists view + enforce 100-list cap

API: GET /api/lists is now ordered alphabetically (COLLATE NOCASE) by title
with no other option, and TodoListController rejects a create past 100 lists
per owner with 409. New TodoListRepository::countForOwner.

Frontend: HomeView replaces the placeholder with the user's lists (rendered in
API order) and a create form (title + optional description). New Pinia lists
store fetches and creates, re-fetching after a create so the new list sorts
into place; it is reset on logout. Form disables and explains at 100 lists;
create errors surface inline. Neutral .badge with a .badge--warn variant;
dropped the unused .facts styles.

Tests: alphabetical ordering and the 100-list cap. Suite: 17 passing.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/Http/Controllers/TodoListController.php

@@ -18,6 +18,7 @@ final class TodoListController extends Controller
 {
     private const TITLE_MAX = 255;
     private const DESCRIPTION_MAX = 2000;
+    private const MAX_LISTS_PER_OWNER = 100;
 
     public function __construct(private readonly TodoListRepository $lists)
     {
@@ -38,12 +39,21 @@ final class TodoListController extends Controller
      */
     public function store(Request $request, Response $response): Response
     {
+        $ownerId = $this->user($request)['id'];
+
         $validator = new Validator($this->body($request));
         $title = $validator->requiredString('title', self::TITLE_MAX);
         $description = $validator->optionalString('description', self::DESCRIPTION_MAX) ?? '';
         $validator->assert();
 
-        $list = $this->lists->create($this->user($request)['id'], $title, $description);
+        if ($this->lists->countForOwner($ownerId) >= self::MAX_LISTS_PER_OWNER) {
+            throw new ApiException(
+                sprintf('You have reached the maximum of %d lists.', self::MAX_LISTS_PER_OWNER),
+                409,
+            );
+        }
+
+        $list = $this->lists->create($ownerId, $title, $description);
 
         return $this->json($response, ['list' => $this->present($list)], 201);
     }