Phase 2: Entity data model extensions for behavior system

- Add Behavior enum (IDLE..FLEE, 11 values) and Trigger enum (DONE,
  BLOCKED, TARGET) as runtime IntEnum classes (closes #297, closes #298)
- Add entity label system: labels property (frozenset), add_label(),
  remove_label(), has_label(), constructor kwarg (closes #296)
- Add cell_pos integer logical position decoupled from float draw_pos;
  grid_pos now aliases cell_pos; SpatialHash::updateCell() for cell-based
  bucket management; FOV/visibility uses cell_position (closes #295)
- Add step callback and default_behavior properties to Entity for
  grid.step() turn management (closes #299)
- Update updateVisibility, visible_entities, ColorLayer::updatePerspective
  to use cell_position instead of float position

BREAKING: grid_pos no longer derives from float x/y position. Use
cell_pos/grid_pos for logical position, draw_pos for render position.

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

src/McRFPy_API.cpp

@@ -16,6 +16,8 @@
 #include "PyKey.h"
 #include "PyMouseButton.h"
 #include "PyInputState.h"
+#include "PyBehavior.h"
+#include "PyTrigger.h"
 #include "PySound.h"
 #include "PySoundBuffer.h"
 #include "PyMusic.h"
@@ -779,6 +781,18 @@ PyObject* PyInit_mcrfpy()
         PyErr_Clear();
     }
 
+    // Add Behavior enum class for entity behavior types (#297)
+    PyObject* behavior_class = PyBehavior::create_enum_class(m);
+    if (!behavior_class) {
+        PyErr_Clear();
+    }
+
+    // Add Trigger enum class for entity step callback triggers (#298)
+    PyObject* trigger_class = PyTrigger::create_enum_class(m);
+    if (!trigger_class) {
+        PyErr_Clear();
+    }
+
     // Add automation submodule
     PyObject* automation_module = McRFPy_Automation::init_automation_module();
     if (automation_module != NULL) {