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/src/style.css

@@ -100,32 +100,46 @@ h1 {
   padding: 0.1rem 0.45rem;
   border-radius: 999px;
   font-size: 0.75rem;
-  border: 1px solid var(--warn-border);
-  background: var(--warn-bg);
+  white-space: nowrap;
+  border: 1px solid var(--border);
+  background: var(--bg);
+  color: var(--muted);
 }
 
-.facts {
-  margin: 1.25rem 0 0;
+.badge--warn {
+  border-color: var(--warn-border);
+  background: var(--warn-bg);
+  color: inherit;
+}
+
+.lists {
+  list-style: none;
+  margin: 1.5rem 0 0;
+  padding: 0;
   display: grid;
   gap: 0.75rem;
 }
 
-.facts div {
+.lists__item {
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  padding: 0.75rem 0.9rem;
+}
+
+.lists__head {
   display: flex;
+  align-items: center;
   justify-content: space-between;
-  gap: 1rem;
-  border-top: 1px solid var(--border);
-  padding-top: 0.6rem;
+  gap: 0.75rem;
 }
 
-.facts dt {
-  color: var(--muted);
+.lists__title {
+  font-weight: 600;
+  word-break: break-word;
 }
 
-.facts dd {
-  margin: 0;
-  text-align: right;
-  word-break: break-all;
+.lists__item .muted {
+  margin: 0.35rem 0 0;
 }
 
 .form {