added missing tooltips

lib/widgets/filter_grids/album_pick.dart

@@ -44,6 +44,7 @@ class AlbumPickAppBar extends StatelessWidget {
         IconButton(
           icon: Icon(AIcons.sort),
           onPressed: () => actionDelegate.onActionSelected(context, ChipSetAction.sort),
+          tooltip: 'Sort…',
         ),
       ],
       floating: true,

lib/widgets/fullscreen/info/info_page.dart

@@ -43,7 +43,7 @@ class InfoPageState extends State<InfoPage> {
         key: Key('back-button'),
         icon: Icon(AIcons.goUp),
         onPressed: _goToImage,
-        tooltip: 'Back to image',
+        tooltip: 'Back to media',
       ),
       title: Text('Info'),
       floating: true,

lib/widgets/search/expandable_filter_row.dart

@@ -45,6 +45,7 @@ class ExpandableFilterRow extends StatelessWidget {
             IconButton(
               icon: Icon(isExpanded ? AIcons.collapse : AIcons.expand),
               onPressed: () => expandedNotifier.value = isExpanded ? null : title,
+              tooltip: isExpanded ? 'Collapse' : 'Expand',
             ),
           ],
         ),

lib/widgets/search/search_button.dart

@@ -16,6 +16,7 @@ class SearchButton extends StatelessWidget {
       key: Key('search-button'),
       icon: Icon(AIcons.search),
       onPressed: () => _goToSearch(context),
+      tooltip: 'Search',
     );
   }