feat(movement): add movement state machine with air/ground/wallrun/slide/dash/ground states

- MovementStateMachine: core state machine base
- MovementParams: export-rich tunable resource
- StateGround/StateAir: grounded & aeriel locomotion with coyote, buffered jump, bunny hop
- StateWallRun / StateWallCling: wall-based traversal with wall-jump off
- StateSlide: sprint-parallel slide with friction fallout
- StateDash: burst dash with momentum brake
- PlayerMovementController: entry point wiring to CharacterBody3D
- input_map.cfg: full action map reference file
- characters/player/player_base.tscn: placeholder scene
- movement/tests/test_fsm_runner.gd: 9-state unit test runner

Closes #1

movement/player_movement_controller.gd

@@ -0,0 +1,50 @@
+extends CharacterBody3D
+class_name PlayerMovementController
+
+## PlayerMovementController — root node for all player 3D locomotion.
+## Attach to a CharacterBody3D with a CollisionShape3D.
+## States are expected to be children: state_ground, state_air,
+## state_wall_run, state_wall_cling, state_slide, state_dash.
+
+signal chain_updated(count: int, bonus: float)
+
+@export var params: MovementParams = preload("res://movement/movement_params.gd").new()
+
+var machine: MovementStateMachine
+var jump_buffered: bool = false
+
+# ── Input references ─────────────────────────────────────────────────────────
+func _unhandled_input(event: InputEvent) -> void:
+	if event.is_action_pressed("ui_accept"):
+		# Space / jump
+		pass
+	_machine.input_jump_just_pressed = Input.is_action_just_pressed("jump")
+	_machine.input_jump_pressed = Input.is_action_pressed("jump")
+	_machine.input_sprint = Input.is_action_pressed("sprint")
+	_machine.input_crouch = Input.is_action_pressed("crouch")
+	_machine.input_dash = Input.is_action_just_pressed("dash")
+	var input_v := Input.get_vector("move_left", "move_right", "move_forward", "move_back")
+	_machine.input_dir = input_v
+
+
+@onready var _machine: MovementStateMachine = $MovementStateMachine
+
+
+func _ready() -> void:
+	_machine.player = self
+	_machine.params = params
+	# Mirror signal up
+	_machine.movement_event.connect(func(ev, data):
+		if ev == "chain_updated":
+			chain_updated.emit(data.count, data.bonus)
+	)
+
+
+func _process(_delta: float) -> void:
+	_machine.input_jump_just_pressed = Input.is_action_just_pressed("jump") and not _machine.input_jump_pressed
+	_machine.input_jump_pressed = Input.is_action_pressed("jump")
+	_machine.input_sprint = Input.is_action_pressed("sprint")
+	_machine.input_crouch = Input.is_action_pressed("crouch")
+	_machine.input_dash = Input.is_action_just_pressed("dash") and not _machine.input_dash
+	var input_v := Input.get_vector("move_left", "move_right", "move_forward", "move_back")
+	_machine.input_dir = input_v