fix: correct add-entry default group and clear search on hide

- GroupFilterViewModel now tracks lastToggledGroupId (the single group
  most recently toggled to a non-empty selection), since toggling a
  group with subgroups expands selectedGroupIds to include the whole
  subtree, breaking the previous count==1 check used to infer the
  active filter group.
- VaultViewModel exposes lastToggledGroupId, forwarded from
  GroupFilterViewModel by VaultRootView (ContentView.swift), and
  EntryListView.defaultGroupId now reads it instead of the broken
  selectedGroupIds.count == 1 check, so the add-entry sheet defaults
  new entries into the group actually being filtered by, not silently
  back to root.
- EntryListView's search toggle button now clears vm.searchQuery when
  hiding the search bar, so a hidden bar can no longer keep filtering
  the list invisibly.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WYqycDFsynHH9VnnK7LNSf

MyPass/Views/EntryListView.swift

@@ -28,7 +28,10 @@ struct EntryListView: View {
         .searchable(text: $vm.searchQuery, isPresented: $isSearching, prompt: "Search entries…")
         .toolbar {
             ToolbarItem(placement: .primaryAction) {
-                Button { isSearching.toggle() } label: {
+                Button {
+                    if isSearching { vm.searchQuery = "" }
+                    isSearching.toggle()
+                } label: {
                     Image(systemName: "magnifyingglass")
                 }
             }
@@ -51,12 +54,10 @@ struct EntryListView: View {
         }
     }
 
-    /// The sole selected filter group if exactly one is active, otherwise the vault root.
+    /// The most recently toggled-on filter group, if any filter is still active via it,
+    /// otherwise the vault root.
     private var defaultGroupId: UUID {
-        if vm.selectedGroupIds.count == 1, let only = vm.selectedGroupIds.first {
-            return only
-        }
-        return vm.session.database?.root.id ?? UUID()
+        vm.lastToggledGroupId ?? vm.session.database?.root.id ?? UUID()
     }
 }