Rework the lists view: form below list, drop description, add count

HomeView now shows a "You have N lists." summary above the list, moves the
new-list form beneath the list, and drops the description input (title only).
lists store createList() loses its description parameter.

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

web/src/style.css

@@ -148,6 +148,12 @@ h1 {
   margin: 1.25rem 0;
 }
 
+.form--new-list {
+  margin-top: 1.5rem;
+  padding-top: 1.25rem;
+  border-top: 1px solid var(--border);
+}
+
 .form label {
   display: grid;
   gap: 0.3rem;