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>

web/README.md

@@ -38,8 +38,9 @@ npm run preview
 src/main.ts            App bootstrap; resolves the stored session before mount
 src/router/index.ts    Routes + guard (redirects to /login when unauthenticated)
 src/stores/auth.ts     Pinia store: token in localStorage, register/login/fetchMe
+src/stores/lists.ts    Pinia store: the user's lists (fetch + create)
 src/lib/api.ts         fetch wrapper, bearer token, typed ApiError
-src/views/             HomeView (placeholder), LoginView, RegisterView
+src/views/             HomeView (lists + create form), LoginView, RegisterView
 ```
 
 ## Auth flow