Initial work on rollback and refactor

src/input/map.rs

@@ -0,0 +1,31 @@
+//! What a physical button means. Device-agnostic: a binding names an
+//! [`InputMapAction`], and each device backend (see [`super::keyboard`])
+//! decides how to read it.
+
+use bevy::prelude::*;
+
+#[derive(Debug)]
+pub enum InputActionState {
+    JustPressed,
+    Pressed,
+    JustReleased,
+    Released,
+}
+
+#[derive(Debug)]
+pub enum InputMapAction {
+    MovementXDir(i32),
+    MovementYDir(i32),
+    Jump,
+}
+
+#[derive(Debug)]
+pub struct KeyboardInputMapElement {
+    pub key: KeyCode,
+    pub action: InputMapAction,
+}
+
+#[derive(Resource)]
+pub struct BaseInputMap {
+    pub keyboard: Vec<KeyboardInputMapElement>,
+}