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/states/state_wall_run.gd

@@ -0,0 +1,88 @@
+extends Node
+class_name StateWallRun
+
+const FLAG: int = 0  # unused
+
+var machine: MovementStateMachine
+var params: MovementParams:
+	get: return machine.params
+
+var elapsed: float = 0.0
+
+
+func enter(_data: Dictionary = {}) -> void:
+	elapsed = 0.0
+	machine.register_chain_mechanic("wall_run")
+	machine.player.velocity.y = params.wall_run_vertical_speed
+
+
+func exit() -> void:
+	pass
+
+
+func update(delta: float) -> void:
+	elapsed += delta
+	if elapsed > params.wall_run_duration:
+		machine.wall_normal = Vector3.ZERO
+		machine.switch_to("air")
+		return
+
+	var vel: Vector3 = machine.player.velocity
+
+	# Stick to wall
+	vel.y = min(vel.y, params.wall_run_vertical_speed)
+
+	# Move along wall: project velocity onto wall tangent
+	var wall_tangent := (machine.wall_normal.cross(Vector3.UP)).normalized()
+	if machine.input_dir.y < 0.0:
+		wall_tangent = -wall_tangent
+	var move_dir: Vector3 = wall_tangent * params.wall_run_speed
+	vel.x = move_dir.x
+	vel.z = move_dir.z
+
+	if machine.input_jump_just_pressed:
+		var jump_vel: Vector3 = vel + (machine.wall_normal * params.wall_run_jump_off_normal)
+		jump_vel.y = params.wall_run_auto_jump_speed
+		machine.player.velocity = jump_vel
+		machine.wall_normal = Vector3.ZERO
+		machine.register_chain_mechanic("wall_jump")
+		machine.switch_to("air")
+		return
+
+	# Wall cling fall-through
+	if machine.input_dir.length() < 0.1:
+		machine.switch_to("wall_cling")
+		return
+
+	# Lose wall contact
+	var still_on_wall := machine.wall_normal != Vector3.ZERO and
+		detect_wall(machine.wall_normal).length_squared() > 0.0
+	if not still_on_wall:
+		machine.wall_normal = Vector3.ZERO
+		machine.register_chain_mechanic("wall_run_off")
+		machine.switch_to("air")
+
+	machine.player.velocity = vel
+	machine.player.move_and_slide()
+
+	if machine.player.is_on_floor():
+		machine.on_ground = true
+		machine.wall_normal = Vector3.ZERO
+		machine.current_jump_count = 0
+		machine.register_chain_mechanic("wall_run_land")
+		machine.switch_to("ground")
+
+
+func detect_wall(expected_normal: Vector3) -> Vector3:
+	var origin := machine.player.global_position
+	var offset := expected_normal.cross(Vector3.UP).normalized()
+	var space_state := machine.player.get_world_3d().direct_space_state
+	for side in [1.0, -1.0]:
+		var ray_origin := origin + offset * side * params.wall_detect_distance + Vector3.UP * params.wall_ray_up_height
+		var ray_end := origin + offset * side * params.wall_detect_distance - Vector3.DOWN * params.wall_ray_down_height
+		var ray := PhysicsRayQueryParameters3D.create(ray_origin, ray_end)
+		ray.exclude = [machine.player.get_rid()]
+		var hit := space_state.intersect_ray(ray)
+		if not hit.is_empty():
+			return hit.get("normal", Vector3.ZERO).normalized()
+	return Vector3.ZERO