Timer refactor: stopwatch-like semantics, mcrfpy.timers collection closes #173

Major Timer API improvements:
- Add `stopped` flag to Timer C++ class for proper state management
- Add `start()` method to restart stopped timers (preserves callback)
- Add `stop()` method that removes from engine but preserves callback
- Make `active` property read-write (True=start/resume, False=pause)
- Add `start=True` init parameter to create timers in stopped state
- Add `mcrfpy.timers` module-level collection (tuple of active timers)
- One-shot timers now set stopped=true instead of clearing callback
- Remove deprecated `setTimer()` and `delTimer()` module functions

Timer callbacks now receive (timer, runtime) instead of just (runtime).
Updated all tests to use new Timer API and callback signature.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/unit/test_headless_click.py

@@ -36,9 +36,7 @@ def test_headless_click():
     automation.click(150, 150)
 
     # Give time for events to process
-    def check_results(runtime):
-        mcrfpy.delTimer("check_click")  # Clean up timer
-
+    def check_results(timer, runtime):
         if len(start_clicks) >= 1:
             print(f"  - Click received: {len(start_clicks)} click(s)")
             # Verify position
@@ -53,7 +51,7 @@ def test_headless_click():
             print(f"  - No clicks received: FAIL")
             sys.exit(1)
 
-    mcrfpy.setTimer("check_click", check_results, 200)
+    mcrfpy.Timer("check_click", check_results, 200, once=True)
 
 
 def test_click_miss():
@@ -84,9 +82,7 @@ def test_click_miss():
     print("  Clicking outside frame at (50, 50)...")
     automation.click(50, 50)
 
-    def check_miss_results(runtime):
-        mcrfpy.delTimer("check_miss")  # Clean up timer
-
+    def check_miss_results(timer, runtime):
         if miss_count[0] == 0:
             print("  - No click on miss: PASS")
             # Now run the main click test
@@ -95,7 +91,7 @@ def test_click_miss():
             print(f"  - Unexpected {miss_count[0]} click(s): FAIL")
             sys.exit(1)
 
-    mcrfpy.setTimer("check_miss", check_miss_results, 200)
+    mcrfpy.Timer("check_miss", check_miss_results, 200, once=True)
 
 
 def test_position_tracking():