Phase 3: Behavior system with grid.step() turn manager

- Add EntityBehavior struct with 11 behavior types: IDLE, CUSTOM,
  NOISE4/8, PATH, WAYPOINT, PATROL, LOOP, SLEEP, SEEK, FLEE.
  Each returns BehaviorOutput (MOVED/DONE/BLOCKED/NO_ACTION) without
  modifying entity position directly (closes #300)
- Add grid.step(n=1, turn_order=None) turn manager: groups entities
  by turn_order, executes behaviors, fires triggers (TARGET/DONE/BLOCKED),
  updates cell_position and spatial hash. Snapshot-based iteration for
  callback safety (closes #301)
- Entity properties: behavior_type (read-only), turn_order, move_speed,
  target_label, sight_radius. Method: set_behavior(type, waypoints,
  turns, path)
- Update ColorLayer::updatePerspective to use cell_position

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/unit/entity_behavior_test.py

@@ -0,0 +1,104 @@
+"""Unit test for #300: EntityBehavior struct and behavior primitives."""
+import mcrfpy
+import sys
+
+def make_grid():
+    """Create a simple 20x20 walkable grid."""
+    scene = mcrfpy.Scene("test300")
+    mcrfpy.current_scene = scene
+    tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16)
+    grid = mcrfpy.Grid(grid_size=(20, 20), texture=tex, pos=(0, 0), size=(320, 320))
+    scene.children.append(grid)
+    for y in range(20):
+        for x in range(20):
+            grid.at(x, y).walkable = True
+            grid.at(x, y).transparent = True
+    return grid
+
+def test_behavior_properties():
+    """Behavior-related properties exist and have correct defaults."""
+    e = mcrfpy.Entity()
+    assert e.behavior_type == 0, f"Default behavior_type should be 0 (IDLE), got {e.behavior_type}"
+    assert e.turn_order == 1, f"Default turn_order should be 1, got {e.turn_order}"
+    assert abs(e.move_speed - 0.15) < 0.01, f"Default move_speed should be 0.15, got {e.move_speed}"
+    assert e.target_label is None, f"Default target_label should be None, got {e.target_label}"
+    assert e.sight_radius == 10, f"Default sight_radius should be 10, got {e.sight_radius}"
+    print("PASS: behavior property defaults")
+
+def test_behavior_property_setters():
+    """Behavior properties can be set."""
+    e = mcrfpy.Entity()
+    e.turn_order = 5
+    assert e.turn_order == 5
+
+    e.move_speed = 0.3
+    assert abs(e.move_speed - 0.3) < 0.01
+
+    e.target_label = "player"
+    assert e.target_label == "player"
+
+    e.target_label = None
+    assert e.target_label is None
+
+    e.sight_radius = 15
+    assert e.sight_radius == 15
+    print("PASS: behavior property setters")
+
+def test_set_behavior_noise():
+    """set_behavior with NOISE4 type."""
+    e = mcrfpy.Entity()
+    e.set_behavior(int(mcrfpy.Behavior.NOISE4))
+    assert e.behavior_type == int(mcrfpy.Behavior.NOISE4)
+    print("PASS: set_behavior NOISE4")
+
+def test_set_behavior_path():
+    """set_behavior with PATH type and pre-computed path."""
+    e = mcrfpy.Entity()
+    path = [(1, 0), (2, 0), (3, 0)]
+    e.set_behavior(int(mcrfpy.Behavior.PATH), path=path)
+    assert e.behavior_type == int(mcrfpy.Behavior.PATH)
+    print("PASS: set_behavior PATH")
+
+def test_set_behavior_patrol():
+    """set_behavior with PATROL type and waypoints."""
+    e = mcrfpy.Entity()
+    waypoints = [(5, 5), (10, 5), (10, 10), (5, 10)]
+    e.set_behavior(int(mcrfpy.Behavior.PATROL), waypoints=waypoints)
+    assert e.behavior_type == int(mcrfpy.Behavior.PATROL)
+    print("PASS: set_behavior PATROL")
+
+def test_set_behavior_sleep():
+    """set_behavior with SLEEP type and turns."""
+    e = mcrfpy.Entity()
+    e.set_behavior(int(mcrfpy.Behavior.SLEEP), turns=5)
+    assert e.behavior_type == int(mcrfpy.Behavior.SLEEP)
+    print("PASS: set_behavior SLEEP")
+
+def test_set_behavior_reset():
+    """set_behavior resets previous behavior state."""
+    e = mcrfpy.Entity()
+    e.set_behavior(int(mcrfpy.Behavior.PATROL), waypoints=[(1,1), (5,5)])
+    assert e.behavior_type == int(mcrfpy.Behavior.PATROL)
+
+    e.set_behavior(int(mcrfpy.Behavior.IDLE))
+    assert e.behavior_type == int(mcrfpy.Behavior.IDLE)
+    print("PASS: set_behavior reset")
+
+def test_turn_order_zero_skip():
+    """turn_order=0 should mean entity is skipped."""
+    e = mcrfpy.Entity()
+    e.turn_order = 0
+    assert e.turn_order == 0
+    print("PASS: turn_order=0")
+
+if __name__ == "__main__":
+    test_behavior_properties()
+    test_behavior_property_setters()
+    test_set_behavior_noise()
+    test_set_behavior_path()
+    test_set_behavior_patrol()
+    test_set_behavior_sleep()
+    test_set_behavior_reset()
+    test_turn_order_zero_skip()
+    print("All #300 tests passed")
+    sys.exit(0)