gmp(M02): add player input intent seam

Work-Package: M02-GMP-INPUT-001
Agent: sindo-main-codex
Tests: verify_player_input; renderer baseline dry-run; coordinate, streaming, documentation and coordination gates
Fidelity: preserves current sandbox bindings and movement/camera behavior; exact build-12340 semantics remain unverified

src/domain/input/move_intent.gd

@@ -0,0 +1,47 @@
+class_name MoveIntent
+extends RefCounted
+
+## Immutable player locomotion request expressed in character-local axes.
+## Axis values are normalized to `[-1, 1]`: forward/right/up are positive.
+## The intent contains no world coordinates, engine input events or presentation state.
+
+var forward_axis: float:
+	get:
+		return _forward_axis
+
+var strafe_axis: float:
+	get:
+		return _strafe_axis
+
+var vertical_axis: float:
+	get:
+		return _vertical_axis
+
+var is_sprint_requested: bool:
+	get:
+		return _is_sprint_requested
+
+var _forward_axis: float
+var _strafe_axis: float
+var _vertical_axis: float
+var _is_sprint_requested: bool
+
+
+## Creates one frame's movement request without retaining mutable input state.
+func _init(
+		forward_axis_value: float = 0.0,
+		strafe_axis_value: float = 0.0,
+		vertical_axis_value: float = 0.0,
+		sprint_requested: bool = false
+) -> void:
+	_forward_axis = clampf(forward_axis_value, -1.0, 1.0)
+	_strafe_axis = clampf(strafe_axis_value, -1.0, 1.0)
+	_vertical_axis = clampf(vertical_axis_value, -1.0, 1.0)
+	_is_sprint_requested = sprint_requested
+
+
+## Returns true when the intent requests planar or vertical translation.
+func has_translation() -> bool:
+	return not is_zero_approx(_forward_axis) \
+		or not is_zero_approx(_strafe_axis) \
+		or not is_zero_approx(_vertical_axis)