Add collapsible dashboard sections with localStorage persistence

Each dashboard section (Profiles, Running, Stopped) now has a chevron
toggle that collapses/expands the section content. Collapsed state is
persisted in localStorage so it survives page reloads and WebSocket
re-renders. Stop All button uses event.stopPropagation() to avoid
triggering the section toggle.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/style.css

@@ -3256,6 +3256,15 @@ input:-webkit-autofill:focus {
     gap: 6px;
     text-transform: uppercase;
     letter-spacing: 0.5px;
+    cursor: pointer;
+    user-select: none;
+}
+
+.dashboard-section-chevron {
+    font-size: 0.6rem;
+    color: var(--text-secondary);
+    width: 10px;
+    display: inline-block;
 }
 
 .dashboard-section-count {