refactor(filter): remove saved filter management from filter page

Removes the IconButton from the HeadlinesFilterPage's AppBar. This action is part of the strategic relocation of the "Manage Saved Filters" feature to the AccountPage, creating a single, dedicated location for this functionality.

Author: fulleni

lib/headlines-feed/view/headlines_filter_page.dart

@@ -274,13 +274,6 @@ class _HeadlinesFilterViewState extends State<_HeadlinesFilterView> {
                       context.pop();
                     },
                   ),
-                  // Manage Saved Filters Button
-                  IconButton(
-                    tooltip: l10n.headlinesFilterManageTooltip,
-                    icon: const Icon(Icons.edit_note_outlined),
-                    onPressed: () =>
-                        context.pushNamed(Routes.manageSavedFiltersName),
-                  ),
                   // Apply Filters Button
                   IconButton(
                     icon: const Icon(Icons.check),