Refactor/cubit to notifier migration

CHANGELOG.md

@@ -1,3 +1,24 @@
+## 0.2.0
+
+> Upgrading from 0.1.x? See [MIGRATION.md](./MIGRATION.md) for a step-by-step guide.
+
+* **Breaking:** We've rebuilt the library on `ValueNotifier` / `ChangeNotifier`. That means `flutter_bloc` and `rxdart` no longer are a dependency.
+* **Breaking:** Renamed core classes:
+  * `FieldCubit` → `FieldController`
+  * `TextFieldCubit` → `TextFieldController`
+  * `BooleanFieldCubit` → `BooleanFieldController`
+  * `SingleSelectFieldCubit` → `SingleSelectFieldController`
+  * `MultiSelectFieldCubit` → `MultiSelectFieldController`
+  * `FormGroupCubit` → `FormGroupController`
+* `FieldBuilder` is kept. It is now a thin wrapper around `ValueListenableBuilder` instead of `BlocBuilder`. The `field:` parameter is now typed `FieldController<T, E>` (previously `FieldCubit<T, E>`); the builder signature is otherwise unchanged. You can also use `ValueListenableBuilder` directly.
+* **Breaking:** Lifecycle method renamed from `close()` to `dispose()` on both controllers.
+* **Breaking:** `FormGroupController` exposes `onValuesChanged` and `onStatusChanged` as `Listenable`s (previously `Stream`s named `onValuesChangedStream` / `onStatusChangedStream`).
+* `TextFieldController` now owns a `TextEditingController` (`field.textController`) kept in two-way sync with the field value. Widgets bind to it directly; programmatic changes (`setValue`, `reset`, `clear`) propagate to the text controller, and user input propagates back. Removes the dual-write bug class around resetting fields, set-to-initial flows, etc.
+* `FieldController` gained an optional `String? name` parameter for debugging, logging, and serialization.
+* `Disposable` mixin removed (lifecycle is handled by `ChangeNotifier.dispose`).
+* Internal `distinctWithFirst` stream extension and `CancelableFuture` are no longer exported.
+* Dropped the `equatable` dependency. `FieldState` and `FormGroupState` now manual `==` / `hashCode`. No behavioral change — value-equality semantics are identical.
+
 ## 0.1.2
 
 * Bumped `bloc` to `^9.0.0`.