Added gameplay_input manager.

Refactored menus, player, and escape_capsule to utilize new system.
Actions defined in Godot project file with default bindings.
Player/Vehicles now react to actions and GameplayInput states instead of polling Input directly.
They respond to commands via `_handle_gameplay_command` and should not implement _unhandled_input directly.
Kept some debugging input handling code in `player.gd` for things like F3/F5/F4/PageUp/PageDown.
We may want to move much of this out of `player.gd` into something that handles the gamestate more generally.

Scenes/Scripts/pause_menu.gd

@@ -17,8 +17,11 @@ func _ready() -> void:
 		quit_button.pressed.connect(_on_quit_to_menu)
 
 
+## Pause has its own binding; menu cancel must not pause during gameplay.
 func _input(event: InputEvent) -> void:
-	if not event.is_action_pressed("ui_cancel"):
+	var pause_pressed := event.is_action_pressed("ui_pause")
+	var cancel_pressed := event.is_action_pressed("ui_cancel")
+	if not pause_pressed and not (visible and cancel_pressed):
 		return
 	var banner := get_node_or_null("/root/Node3D/HUD/ScrambleBanner")
 	if banner and banner.visible:
@@ -27,6 +30,8 @@ func _input(event: InputEvent) -> void:
 		_on_resume()
 		get_viewport().set_input_as_handled()
 		return
+	if not GameplayInput.gameplay_enabled():
+		return
 	var p := get_tree().get_first_node_in_group("player")
 	if p == null:
 		p = get_node_or_null("/root/Node3D/Player")
@@ -35,16 +40,21 @@ func _input(event: InputEvent) -> void:
 		get_viewport().set_input_as_handled()
 
 
+## Blocks gameplay and selects a controller-accessible control before pausing.
 func open_pause(player_ref: Node) -> void:
 	player = player_ref
 	visible = true
+	GameplayInput.set_menu_open(self, true)
+	resume_button.grab_focus()
 	Input.mouse_mode = Input.MOUSE_MODE_VISIBLE
 	get_tree().paused = true
 
 
+## Restores control only after currently held gameplay inputs return to neutral.
 func _on_resume() -> void:
 	visible = false
 	get_tree().paused = false
+	GameplayInput.set_menu_open(self, false)
 	Input.mouse_mode = Input.MOUSE_MODE_CAPTURED
 
 
@@ -59,5 +69,6 @@ func _on_save() -> void:
 
 func _on_quit_to_menu() -> void:
 	get_tree().paused = false
+	GameplayInput.set_menu_open(self, false)
 	Input.mouse_mode = Input.MOUSE_MODE_VISIBLE
 	get_tree().change_scene_to_file("res://Scenes/main_menu.tscn")