Add stage 5: list detail page with items UI and drag reorder

API: new PUT /api/lists/{id}/items/order takes the full ordered id set and
rewrites positions 0..n-1 in a transaction (422 unless the set matches the
list exactly). TodoItemRepository gains idsForList() and reorder().

Frontend: lists on the home page are now links to /lists/:id (ListView).
ListView shows the list title, a "M of N done" summary, and each item as a
drag handle + checkbox + inline-editable text (saved on blur) + delete
button, with a create-item form at the bottom. Drag-and-drop uses
vuedraggable; on drop the whole order is persisted via the new endpoint and
the response replaces local state, with a resync-on-error fallback. New
items store; items store is also reset on logout.

Tests: reorder happy path, incomplete-set rejection, owner scoping. Backend
suite: 23 passing.

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

src/bootstrap.php

@@ -70,6 +70,7 @@ $app->group('/api', function (RouteCollectorProxy $group) use (
 
         $lists->get('/{listId:[0-9]+}/items', [$itemController, 'index']);
         $lists->post('/{listId:[0-9]+}/items', [$itemController, 'store']);
+        $lists->put('/{listId:[0-9]+}/items/order', [$itemController, 'reorder']);
         $lists->get('/{listId:[0-9]+}/items/{itemId:[0-9]+}', [$itemController, 'show']);
         $lists->patch('/{listId:[0-9]+}/items/{itemId:[0-9]+}', [$itemController, 'update']);
         $lists->delete('/{listId:[0-9]+}/items/{itemId:[0-9]+}', [$itemController, 'destroy']);