Add a Settings option to reorder the selection action bar's actions

NooSelectionBar's fixed inline slots (3 mobile / 4 desktop, the rest
behind "More") previously just took the first N actions in whatever
order each screen happened to build them in. Give bulk actions a
stable SelectionActionKind identity (independent of their dynamic
icon/label, e.g. favorite vs. unfavorite) so Settings can offer a
drag-to-reorder list - mirroring the existing Tabs section, minus the
pin/hide concept, which doesn't apply here - and each screen applies
that saved priority order via orderSelectionActions before handing
its action list to the bar.

lib/models/selection_action.dart

@@ -1,16 +1,91 @@
 import 'package:flutter/material.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+
+/// A bulk action's identity, stable across the dynamic icon/label a
+/// [SelectionAction] actually renders (e.g. `favorite` covers both
+/// "Favorite" and "Remove from favorites"). This is what the user's
+/// configured [order] - Settings' "Action bar" reorder list - and
+/// [NooSelectionBar]'s inline/overflow split key off, since the live
+/// [SelectionAction] list is rebuilt fresh on every selection change and
+/// can't be compared by icon/label alone.
+///
+/// Not every screen offers every kind (e.g. Favorites has no `rename` or
+/// `sync`) - [orderSelectionActions] just skips whatever kind a screen
+/// didn't build.
+enum SelectionActionKind {
+  favorite,
+  share,
+  download,
+  delete,
+  copy,
+  move,
+  rename,
+  sync,
+  details;
+
+  /// Generic label for the Settings reorder row - the live bar uses each
+  /// screen's own contextual label (e.g. "Remove from favorites") instead.
+  String get label => switch (this) {
+    SelectionActionKind.favorite => 'Favorite',
+    SelectionActionKind.share => 'Share',
+    SelectionActionKind.download => 'Download',
+    SelectionActionKind.delete => 'Delete',
+    SelectionActionKind.copy => 'Copy',
+    SelectionActionKind.move => 'Move',
+    SelectionActionKind.rename => 'Rename',
+    SelectionActionKind.sync => 'Sync to device',
+    SelectionActionKind.details => 'Details',
+  };
+
+  IconData get icon => switch (this) {
+    SelectionActionKind.favorite => LucideIcons.star,
+    SelectionActionKind.share => LucideIcons.share2,
+    SelectionActionKind.download => LucideIcons.download,
+    SelectionActionKind.delete => LucideIcons.trash2,
+    SelectionActionKind.copy => LucideIcons.copy,
+    SelectionActionKind.move => LucideIcons.folderInput,
+    SelectionActionKind.rename => LucideIcons.filePen,
+    SelectionActionKind.sync => LucideIcons.hardDriveDownload,
+    SelectionActionKind.details => LucideIcons.info,
+  };
+}
 
 /// One bulk action available for the current multi-selection (e.g. favorite,
 /// download, delete), shown as an icon button in the sticky selection
 /// toolbar each tab (Files, Photos, ...) renders inline in its own content.
 class SelectionAction {
+  final SelectionActionKind kind;
   final IconData icon;
   final String label;
   final VoidCallback onTap;
 
   const SelectionAction({
+    required this.kind,
     required this.icon,
     required this.label,
     required this.onTap,
   });
 }
+
+/// Reorders [actions] to match the user's configured [order] (Settings'
+/// "Action bar" section, [SelectionActionKind] values) - this is what makes
+/// that setting take effect, since it's [order] that decides which actions
+/// land in `NooSelectionBar`'s inline slots vs. behind "More". A kind in
+/// [order] the caller didn't build (e.g. `rename` on a multi-item
+/// selection) is just skipped; a kind [actions] has that [order] doesn't
+/// mention (e.g. a kind added in a later app update, before the saved
+/// order is migrated - see [SettingsController.selectionActionOrder]) is
+/// appended at the end in its original position.
+List<SelectionAction> orderSelectionActions(
+  List<SelectionAction> actions,
+  List<SelectionActionKind> order,
+) {
+  final byKind = {for (final a in actions) a.kind: a};
+  final ordered = <SelectionAction>[];
+  for (final kind in order) {
+    final action = byKind.remove(kind);
+    if (action != null) ordered.add(action);
+  }
+  ordered.addAll(byKind.values);
+  return ordered;
+}