feat: Implement comprehensive mouse event system

Implements multiple mouse event improvements for UI elements:

- Mouse enter/exit events (#140): on_enter, on_exit callbacks and
  hovered property for all UIDrawable types (Frame, Caption, Sprite, Grid)
- Headless click events (#111): Track simulated mouse position for
  automation testing in headless mode
- Mouse move events (#141): on_move callback fires continuously while
  mouse is within element bounds
- Grid cell events (#142): on_cell_enter, on_cell_exit, on_cell_click
  callbacks with cell coordinates (x, y), plus hovered_cell property

Includes comprehensive tests for all new functionality.

Closes #140, closes #111, closes #141, closes #142

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/unit/test_headless_click.py

@@ -0,0 +1,126 @@
+#!/usr/bin/env python3
+"""Test #111: Click Events in Headless Mode"""
+
+import mcrfpy
+from mcrfpy import automation
+import sys
+
+# Track callback invocations
+click_count = 0
+click_positions = []
+
+def test_headless_click():
+    """Test that clicks work in headless mode via automation API"""
+    print("Testing headless click events...")
+
+    mcrfpy.createScene("test_click")
+    ui = mcrfpy.sceneUI("test_click")
+    mcrfpy.setScene("test_click")
+
+    # Create a frame at known position
+    frame = mcrfpy.Frame(pos=(100, 100), size=(200, 200))
+    ui.append(frame)
+
+    # Track only "start" events (press) - click() sends both press and release
+    start_clicks = []
+
+    def on_click_handler(x, y, button, action):
+        if action == "start":
+            start_clicks.append((x, y, button, action))
+            print(f"    Click received: x={x}, y={y}, button={button}, action={action}")
+
+    frame.on_click = on_click_handler
+
+    # Use automation to click inside the frame
+    print("  Clicking inside frame at (150, 150)...")
+    automation.click(150, 150)
+
+    # Give time for events to process
+    def check_results(runtime):
+        mcrfpy.delTimer("check_click")  # Clean up timer
+
+        if len(start_clicks) >= 1:
+            print(f"  - Click received: {len(start_clicks)} click(s)")
+            # Verify position
+            pos = start_clicks[0]
+            assert pos[0] == 150, f"Expected x=150, got {pos[0]}"
+            assert pos[1] == 150, f"Expected y=150, got {pos[1]}"
+            print(f"  - Position correct: ({pos[0]}, {pos[1]})")
+            print("  - headless click: PASS")
+            print("\n=== All Headless Click tests passed! ===")
+            sys.exit(0)
+        else:
+            print(f"  - No clicks received: FAIL")
+            sys.exit(1)
+
+    mcrfpy.setTimer("check_click", check_results, 200)
+
+
+def test_click_miss():
+    """Test that clicks outside an element don't trigger its callback"""
+    print("Testing click miss (outside element)...")
+
+    global click_count, click_positions
+    click_count = 0
+    click_positions = []
+
+    mcrfpy.createScene("test_miss")
+    ui = mcrfpy.sceneUI("test_miss")
+    mcrfpy.setScene("test_miss")
+
+    # Create a frame at known position
+    frame = mcrfpy.Frame(pos=(100, 100), size=(100, 100))
+    ui.append(frame)
+
+    miss_count = [0]  # Use list to avoid global
+
+    def on_click_handler(x, y, button, action):
+        miss_count[0] += 1
+        print(f"    Unexpected click received at ({x}, {y})")
+
+    frame.on_click = on_click_handler
+
+    # Click outside the frame
+    print("  Clicking outside frame at (50, 50)...")
+    automation.click(50, 50)
+
+    def check_miss_results(runtime):
+        mcrfpy.delTimer("check_miss")  # Clean up timer
+
+        if miss_count[0] == 0:
+            print("  - No click on miss: PASS")
+            # Now run the main click test
+            test_headless_click()
+        else:
+            print(f"  - Unexpected {miss_count[0]} click(s): FAIL")
+            sys.exit(1)
+
+    mcrfpy.setTimer("check_miss", check_miss_results, 200)
+
+
+def test_position_tracking():
+    """Test that automation.position() returns simulated position"""
+    print("Testing position tracking...")
+
+    # Move to a specific position
+    automation.moveTo(123, 456)
+
+    # Check position
+    pos = automation.position()
+    print(f"  Position after moveTo(123, 456): {pos}")
+
+    assert pos[0] == 123, f"Expected x=123, got {pos[0]}"
+    assert pos[1] == 456, f"Expected y=456, got {pos[1]}"
+
+    print("  - position tracking: PASS")
+
+
+if __name__ == "__main__":
+    try:
+        test_position_tracking()
+        test_click_miss()  # This will chain to test_headless_click on success
+    except Exception as e:
+        print(f"\nTEST FAILED: {e}")
+        import traceback
+        traceback.print_exc()
+        sys.exit(1)