refactor(ui): declutter extension card actions

Drop homepage/GitHub buttons from store extension cards (they remain on
the detail page); keep them only for unlisted extensions whose cards do
not open a detail view. With the labeled update button this caps card
actions at update/settings/delete.

ui/flutter/lib/features/extensions/presentation/pages/extensions_page.dart

@@ -1095,13 +1095,15 @@ class _ExtensionCard extends ConsumerWidget {
                           ? const SizedBox.square(dimension: 14, child: shad.CircularProgressIndicator())
                           : const Icon(Icons.download),
                     ),
-                  if ((item.homepage ?? '').isNotEmpty)
+                  // Unlisted extensions have no detail page to open, so keep
+                  // their links reachable directly on the card.
+                  if (item.store == null && (item.homepage ?? '').isNotEmpty)
                     shad.GhostButton(
                       density: shad.ButtonDensity.icon,
                       onPressed: () => unawaited(launchUrl(Uri.parse(item.homepage!))),
                       child: const Icon(Icons.home_outlined),
                     ),
-                  if ((item.repoUrl ?? '').isNotEmpty)
+                  if (item.store == null && (item.repoUrl ?? '').isNotEmpty)
                     shad.GhostButton(
                       density: shad.ButtonDensity.icon,
                       onPressed: () => unawaited(launchUrl(Uri.parse(item.repoUrl!))),