Ad and purchases enabled (still need actual testing)

lib/services/cloud/cloud_storage_provider.dart

@@ -95,6 +95,16 @@ abstract class CloudStorageSession {
   /// if none exists. If duplicates exist, the earliest-created one wins.
   Future<String> findOrCreateFolder({required String parentId, required String name});
 
+  /// Relocates the existing folder [folderId] to be a child of
+  /// [newParentId] instead of wherever it currently lives, preserving its
+  /// contents and (name/subtree) intact. Used when the user picks a
+  /// different location for the app's already-existing folder (see
+  /// [CloudSyncService.selectAppFolder]), so its synced data and receipts
+  /// move with it instead of being abandoned in place while a fresh, empty
+  /// folder is created at the new location. Returns the folder's
+  /// (possibly new, for a path-addressed provider) id.
+  Future<String> moveFolder({required String folderId, required String newParentId});
+
   /// Looks up a file's ID + versionTag by name within [folderId] without
   /// downloading its content, or null if no such file exists yet.
   Future<CloudFileInfo?> findFile({required String folderId, required String name});

lib/services/cloud/dropbox_provider.dart

@@ -244,6 +244,17 @@ class DropboxSession implements CloudStorageSession {
     return childPath;
   }
 
+  @override
+  Future<String> moveFolder({required String folderId, required String newParentId}) async {
+    final name = folderId.substring(folderId.lastIndexOf('/') + 1);
+    final toPath = _childPath(newParentId, name);
+    if (toPath == folderId) return folderId;
+
+    final json = await _post('/2/files/move_v2', {'from_path': folderId, 'to_path': toPath});
+    final metadata = json['metadata'] as Map<String, dynamic>?;
+    return metadata?['path_display'] as String? ?? toPath;
+  }
+
   @override
   Future<CloudFileInfo?> findFile({required String folderId, required String name}) async {
     final filePath = _childPath(folderId, name);

lib/services/cloud/google_drive_provider.dart

@@ -157,6 +157,20 @@ class GoogleDriveSession implements CloudStorageSession {
     return created.id!;
   }
 
+  @override
+  Future<String> moveFolder({required String folderId, required String newParentId}) async {
+    final current = await _api.files.get(folderId, $fields: 'parents') as drive.File;
+    final oldParents = (current.parents ?? []).join(',');
+    final updated = await _api.files.update(
+      drive.File(),
+      folderId,
+      addParents: newParentId,
+      removeParents: oldParents.isEmpty ? null : oldParents,
+      $fields: 'id',
+    );
+    return updated.id ?? folderId;
+  }
+
   @override
   Future<CloudFileInfo?> findFile({required String folderId, required String name}) async {
     final result = await _api.files.list(

lib/services/cloud/onedrive_provider.dart

@@ -245,6 +245,22 @@ class OneDriveSession implements CloudStorageSession {
     return created['id'] as String;
   }
 
+  @override
+  Future<String> moveFolder({required String folderId, required String newParentId}) async {
+    final response = await http.patch(
+      _graph('/me/drive/${_itemSegment(folderId)}'),
+      headers: {...await _authHeader(), 'Content-Type': 'application/json'},
+      body: jsonEncode({
+        'parentReference': {'id': newParentId},
+      }),
+    );
+    if (response.statusCode != 200) {
+      throw StateError('OneDrive API error (moveFolder): ${response.statusCode} ${response.body}');
+    }
+    final json = jsonDecode(response.body) as Map<String, dynamic>;
+    return json['id'] as String? ?? folderId;
+  }
+
   @override
   Future<CloudFileInfo?> findFile({required String folderId, required String name}) async {
     final uri = _graph('/me/drive/${_itemSegment(folderId)}:/$name');

lib/services/cloud/webdav_provider.dart

@@ -282,6 +282,22 @@ class WebDavSession implements CloudStorageSession {
     return childUri.path;
   }
 
+  @override
+  Future<String> moveFolder({required String folderId, required String newParentId}) async {
+    final name = _nameFromPath(folderId);
+    final destination = _childUri(_uriFor(newParentId), name);
+
+    final response = await _send('MOVE', _uriFor(folderId), headers: {
+      'Authorization': _provider._authHeader,
+      'Destination': destination.toString(),
+      'Overwrite': 'F',
+    });
+    if (response.statusCode != 201 && response.statusCode != 204) {
+      throw StateError('WebDAV MOVE failed: ${response.statusCode} ${response.body}');
+    }
+    return destination.path;
+  }
+
   @override
   Future<CloudFileInfo?> findFile({required String folderId, required String name}) async {
     final fileUri = _childUri(_uriFor(folderId), name);