refactor: 使用flutter对原先的web项目重构，正在进行中

app/lib/src/core/input.dart

@@ -0,0 +1,124 @@
+// 输入：IWBT 经典键位（Shift 跳 / Z 跳 / X 射击 / R 重来）。
+// 与 web 版 input.js 1:1 对应。键码沿用 Web 的 KeyboardEvent.code 字符串，
+// 由 UI 层的键盘监听器把 Flutter 按键翻译成 code 后喂给 onKey()。
+import 'dart:convert';
+
+class Input {
+  /// 动作 -> 默认绑定的按键 code 列表。
+  static final Map<String, List<String>> bind = {
+    'left': ['ArrowLeft', 'KeyA'],
+    'right': ['ArrowRight', 'KeyD'],
+    'up': ['ArrowUp', 'KeyW'],
+    'down': ['ArrowDown', 'KeyS'],
+    'jump': ['ShiftLeft', 'ShiftRight', 'Space', 'KeyZ', 'KeyN'],
+    'shoot': ['KeyX', 'KeyJ', 'KeyC', 'KeyM'],
+    'suicide': ['KeyR'], // IWBT 标准：自杀并回到最近存档点
+    'restart': ['Backspace'], // 整关从头再来（放弃所有存档点）
+    'pause': ['Escape', 'KeyP'],
+    'menu': ['KeyQ'],
+  };
+
+  static final List<String> actions =
+      bind.keys.toList(); // ['left','right',...]
+
+  static final Map<String, List<String>> _defaultBind = {
+    for (final e in bind.entries) e.key: List<String>.from(e.value),
+  };
+
+  static final Set<String> down = {}; // 当前按住的原始 code
+  static final Map<String, bool> now = {for (final a in bind.keys) a: false};
+  static final Map<String, bool> prev = {for (final a in bind.keys) a: false};
+  static final Map<String, bool> touch = {}; // 触屏虚拟按键 action -> bool
+
+  static bool enabled = true;
+
+  static bool held(String a) => now[a] ?? false;
+  static bool hit(String a) => (now[a] ?? false) && !(prev[a] ?? false);
+  static bool released(String a) => !(now[a] ?? false) && (prev[a] ?? false);
+  static bool raw(String c) => down.contains(c);
+  static bool anyHit() {
+    for (final k in now.keys) {
+      if (now[k]! && !(prev[k] ?? false)) return true;
+    }
+    return false;
+  }
+
+  static void clear() {
+    down.clear();
+    for (final k in now.keys) now[k] = false;
+    for (final k in prev.keys) prev[k] = false;
+  }
+
+  /// 每逻辑帧末尾调用。
+  static void endFrame() {
+    for (final k in now.keys) prev[k] = now[k]!;
+  }
+
+  static void _refresh() {
+    for (final act in bind.keys) {
+      bool v = false;
+      for (final c in bind[act]!) {
+        if (down.contains(c)) {
+          v = true;
+          break;
+        }
+      }
+      if (touch[act] ?? false) v = true;
+      now[act] = enabled ? v : false;
+    }
+  }
+
+  /// 原始键盘事件（Web code 字符串）。
+  static void onKey(String code, bool isDown) {
+    if (isDown) {
+      down.add(code);
+    } else {
+      down.remove(code);
+    }
+    _refresh();
+  }
+
+  // ---------------- 触屏虚拟按键 ----------------
+  static void setTouch(String action, bool on) {
+    touch.putIfAbsent(action, () => false);
+    if (touch[action] == on) return;
+    touch[action] = on;
+    _refresh();
+  }
+
+  static void clearTouch() {
+    bool any = false;
+    for (final k in touch.keys) {
+      if (touch[k]!) {
+        touch[k] = false;
+        any = true;
+      }
+    }
+    if (any) _refresh();
+  }
+
+  // ---------------- 键位自定义（设置界面调用）----------------
+  static Map<String, List<String>> defaultBindings() =>
+      {for (final e in bind.entries) e.key: List<String>.from(e.value)};
+
+  static Map<String, List<String>> snapshotBindings() =>
+      {for (final e in bind.entries) e.key: List<String>.from(e.value)};
+
+  static void applyBindings(Map<String, List<String>>? map) {
+    if (map == null) return;
+    for (final act in map.keys) {
+      if (bind.containsKey(act)) bind[act] = List<String>.from(map[act]!);
+    }
+  }
+
+  /// 持久化用：转 JSON 字符串。
+  static String toJson() => jsonEncode(bind);
+  static void fromJson(String? s) {
+    if (s == null) return;
+    try {
+      final m = (jsonDecode(s) as Map).cast<String, dynamic>();
+      final decoded = m.map((k, v) => MapEntry(k, List<String>.from(v as List)));
+      applyBindings(decoded);
+    } catch (_) {}
+  }
+}