feat: Add build info and localization for entry app

- Introduced buildinfo.json5 to enable impeller feature.
- Added Chinese localization strings in string.json for module description and entry ability.
- Created Ability.test.ets for unit testing of ability functionalities.
- Implemented List.test.ets to run the ability tests.
- Developed TestAbility.ets to manage test execution and lifecycle events.
- Created Index.ets as a testability page with UI components.
- Added OpenHarmonyTestRunner.ts for managing test execution in OpenHarmony.
- Defined module.json5 for entry_test module configuration.
- Established color.json and string.json for base resources.
- Included icon.png for the test module.
- Created test_pages.json to define testability page sources.
- Configured hvigor and oh-package.json5 for project setup.
- Updated pubspec.yaml and related files to downgrade Dart SDK to 3.11.0 and adjust dependencies.
- Added PowerShell script to enable OpenHarmony Flutter toolchain.
- Updated multiple package pubspec.yaml files to align with Dart SDK version 3.11.0 and adjust dependencies accordingly.

docs/01-project-structure.md

@@ -81,7 +81,7 @@ conti-app/
 | 项 | 版本 | 说明 |
 |---|---|---|
 | Flutter | **3.44.9** | 用 [FVM](https://fvm.app/) 锁定，仓库根目录提交 `.fvmrc` |
-| Dart | 随 Flutter 3.44.9 附带（3.12.x） | 具体号以 `flutter --version` 实测为准；`environment: sdk: ^3.12.0` 对整个 3.12.x 都成立 |
+| Dart | 随 Flutter 3.44.9 附带（3.12.x） | 具体号以 `flutter --version` 实测为准；`environment: sdk: ^3.11.0` 对整个 3.12.x 都成立 |
 
 **为什么不跟最新 stable（3.47.0 / Dart 3.13.0，2026-08-12 发布）**：鸿蒙（OpenHarmony）的 Flutter 分支适配落后于官方 stable 一段时间，虽然 OHOS 不在首版范围（见 [07-native-integration.md](./07-native-integration.md) 的「OHOS 后续演进」），但 SDK 基线要为后续接 OHOS 留出兼容窗口，所以刻意停在 3.44.9 而不是追最新。这条约束在决定升级 Flutter 版本时必须重新评估，不要因为"新版本有新特性"就单方面升。
 
@@ -109,7 +109,7 @@ Melos 7.0 起改用 Dart 官方原生的 **[Pub Workspaces](https://dart.dev/too
 name: conti_app
 publish_to: none
 environment:
-  sdk: ^3.12.0
+  sdk: ^3.11.0
 
 workspace:
   - app