Rework input buffer to match HDR closer (#79)

## Summary

- Preserve distinct same-action bindings in rollback input frames.
- Add independent command lifetimes with tap and state-scoped hold buffering.
- Detect second shield bindings and consume shield commands for air dodge.
- Fix duplicate keyboard mappings being overwritten.

Reviewed-on: #79
Co-authored-by: Álex Román Núñez <eirexe@eirteam.moe>

src/input/keyboard.rs

@@ -30,9 +30,15 @@ pub fn sample_keyboard(key: &ButtonInput<KeyCode>, input_map: &BaseInputMap) ->
             InputMapAction::MovementYDir(sign) => {
                 input_frame.movement.y += (sign) * action_strength
             }
-            InputMapAction::Jump => input_frame.jump = action_strength != FGi32::ZERO,
-            InputMapAction::Shield => input_frame.shield = action_strength != FGi32::ZERO,
-            InputMapAction::Attack => input_frame.attack = action_strength != FGi32::ZERO,
+            InputMapAction::Jump | InputMapAction::Shield | InputMapAction::Attack => {
+                if let Some(action) = keyboard_elment.action.digital_action() {
+                    input_frame.bindings.set(
+                        action,
+                        keyboard_elment.binding_slot,
+                        action_strength != FGi32::ZERO,
+                    );
+                }
+            }
         }
     }