Add XNN Pack toggle switch for ONNX inference acceleration (#155)

* Initial plan

* Add XNN Pack switch for ONNX inference acceleration

Co-authored-by: xkeyC <39891083+xkeyC@users.noreply.github.com>

* Refactor Rust ONNX session creation to reduce code duplication

Co-authored-by: xkeyC <39891083+xkeyC@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xkeyC <39891083+xkeyC@users.noreply.github.com>

lib/common/rust/api/ort_api.dart

@@ -12,15 +12,18 @@ import 'package:flutter_rust_bridge/flutter_rust_bridge_for_generated.dart';
 /// * `model_path` - 模型文件夹路径
 /// * `model_key` - 模型缓存键（用于标识模型，如 "zh-en"）
 /// * `quantization_suffix` - 量化后缀（如 "_q4", "_q8"，空字符串表示使用默认模型）
+/// * `use_xnnpack` - 是否使用 XNNPACK 加速
 ///
 Future<void> loadTranslationModel({
   required String modelPath,
   required String modelKey,
   required String quantizationSuffix,
+  required bool useXnnpack,
 }) => RustLib.instance.api.crateApiOrtApiLoadTranslationModel(
   modelPath: modelPath,
   modelKey: modelKey,
   quantizationSuffix: quantizationSuffix,
+  useXnnpack: useXnnpack,
 );
 
 /// 翻译文本