迁移 Flutter 端与训练脚本，模型/训练产物移出 git（遵循纯代码约定）

flutter_app/lib/camera/motion_detector.dart

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+import 'dart:typed_data';
+
+import '../detection/detection_result.dart';
+import '../detection/motion_aggregator.dart';
+
+/// 轻量运动检测：相邻帧 Y 通道差分 + 分块聚合。
+/// 小尺寸工作（约 128x128 内），在分析流中串行调用。
+/// 相机大幅移动时（全屏帧差）自动忽略本帧，避免误报。
+class MotionDetector {
+  final int maxWidth;
+  final int maxHeight;
+
+  List<int>? _prevGray;
+
+  MotionDetector({this.maxWidth = 128, this.maxHeight = 128});
+
+  /// 后台 isolate 用原始数据接口（不依赖 CameraImage）。
+  List<MotionRegion> detectMotionRaw(
+      Uint8List yPlane, int yStride, int width, int height) {
+    final w = width, h = height;
+    final scale = maxWidth / w < maxHeight / h ? maxWidth / w : maxHeight / h;
+    final tw = (w * scale).toInt().clamp(1, maxWidth);
+    final th = (h * scale).toInt().clamp(1, maxHeight);
+    if (tw == 0 || th == 0) return const [];
+
+    // 取 Y 平面缩放灰度（最近邻下采样到 128x128 内）
+    final y = yPlane;
+    final gray = List<int>.filled(tw * th, 0);
+    for (var oy = 0; oy < th; oy++) {
+      final sy = (oy / scale).toInt().clamp(0, h - 1);
+      for (var ox = 0; ox < tw; ox++) {
+        final sx = (ox / scale).toInt().clamp(0, w - 1);
+        gray[oy * tw + ox] = y[sy * yStride + sx];
+      }
+    }
+
+    final prev = _prevGray;
+    _prevGray = List.of(gray);
+    if (prev == null || prev.length != gray.length) return const [];
+
+    final diff = MotionAggregator.diffMask(gray, prev);
+    final motionTotal = diff.fold(0, (a, b) => a + b);
+    // 全屏大差异 → 相机移动/大范围变化，忽略本帧
+    if (motionTotal > tw * th / 2) return const [];
+    if (motionTotal < 12) return const [];
+    return MotionAggregator.aggregate(diff, tw, th);
+  }
+
+  /// 相机切换后重置参考帧，避免旧帧误差
+  void reset() {
+    _prevGray = null;
+  }
+}