feat: add pluggable alarm styles and migrate wecker.py

Introduce a styles/ plugin package:
- styles/base.py: AlarmStyle ABC (injected set_led, update()->bool contract)
- styles/blink.py: BlinkStyle, the existing count-the-blinks puzzle moved
  out of wecker.py's AlarmClock
- styles/simple.py: SimpleStyle, press-once-to-stop (the new default style)
- styles/__init__.py: STYLES registry + get_style() validator + LEGACY_STYLE

wecker.py now resolves the style via the registry and owns only the shared
music/button/cleanup loop; the --style CLI arg defaults to blink so existing
cron entries keep their behaviour. Unknown styles raise before hardware init.

tests/test_wecker.py

@@ -33,104 +33,32 @@ def test_set_led(mock_gpio):
 
 
 @patch("wecker.time.time")
-def test_run_alarm_start_to_wait(mock_time, mock_gpio, mock_pygame):
-    # Mock pygame.mixer.get_init() to return True so music plays
+def test_run_alarm_plays_music(mock_time, mock_gpio, mock_pygame):
     mock_pygame.mixer.get_init.return_value = True
-
-    # Just run it in test mode, it should execute the loop once and exit
     wecker.run_alarm(test_mode=True)
     assert mock_pygame.mixer.music.play.called
 
 
-def test_state_machine_evaluation(mock_gpio, mock_pygame):
-    clock = wecker.AlarmClock()
-
-    # Transition to ringing -> wait before blink
-    clock.update(100.0, True)  # button press
-    assert clock.state == wecker.STATE_WAIT_BEFORE_BLINK
-
-    # Wait 3 seconds -> blinking
-    with patch("wecker.random.randint", return_value=3):
-        clock.update(103.1, False)
-    assert clock.state == wecker.STATE_BLINKING
-    assert clock.target_blinks == 3
-
-    # Advance time past the blink sequence (3 blinks * 2 phases * 0.3s = 1.8s)
-    clock.update(105.0, False)
-    assert clock.state == wecker.STATE_WAIT_FOR_INPUT
-
-    # Press 1
-    clock.update(105.5, True)
-    clock.update(105.6, False)
-    # Press 2
-    clock.update(106.0, True)
-    clock.update(106.1, False)
-    # Press 3
-    clock.update(106.5, True)
-    clock.update(106.6, False)
-
-    assert clock.user_presses == 3
-
-    # Wait 3 seconds to evaluate
-    clock.update(109.7, False)  # Triggers state change
-    keep_running = clock.update(109.8, False)  # Triggers evaluation
-
-    # It should evaluate, see it's correct, and return False (stop running)
-    assert clock.state == wecker.STATE_EVALUATING
-    assert not keep_running
+def test_run_alarm_unknown_style_raises(mock_gpio, mock_pygame):
+    """An unknown style is rejected before any hardware is touched."""
+    with pytest.raises(ValueError, match="Unknown alarm style"):
+        wecker.run_alarm(style_name="nope", test_mode=True)
+    mock_pygame.mixer.init.assert_not_called()
 
 
-def test_state_machine_incorrect(mock_gpio, mock_pygame):
-    clock = wecker.AlarmClock()
-    clock.state = wecker.STATE_WAIT_FOR_INPUT
-    clock.target_blinks = 3
+def test_run_alarm_uses_selected_style(mock_gpio, mock_pygame):
+    """run_alarm looks up the style by name and drives the returned style."""
+    mock_pygame.mixer.get_init.return_value = True
+    fake = MagicMock()
+    fake.update.return_value = True  # keep ringing
+    fake_style_cls = MagicMock(return_value=fake)
 
-    # Only press once
-    clock.update(100.0, True)
-    clock.update(100.1, False)
+    with patch("wecker.get_style", return_value=fake_style_cls) as get_style:
+        wecker.run_alarm(style_name="whatever", test_mode=True)
 
-    # Wait to evaluate
-    clock.last_interaction_time = 100.1
-    clock.update(103.2, False)  # triggers eval state
-    keep_running = clock.update(103.3, False)  # evals to incorrect
-
-    # Evaluated incorrectly, should wait before retry
-    assert keep_running
-    assert clock.state == wecker.STATE_WAIT_BEFORE_RETRY
-
-
-def test_blinking_is_non_blocking(mock_gpio, mock_pygame):
-    clock = wecker.AlarmClock()
-    clock.state = wecker.STATE_BLINKING
-    clock.target_blinks = 2
-
-    # Start of blinking: LED on
-    clock.update(100.0, False)
-    assert clock.state == wecker.STATE_BLINKING
-    mock_gpio.output.assert_called_with(wecker.LED_PIN, mock_gpio.LOW)
-
-    # Mid-blink: LED toggles based on elapsed time
-    clock.update(100.3, False)
-    mock_gpio.output.assert_called_with(wecker.LED_PIN, mock_gpio.HIGH)
-
-    # After sequence completes (2 blinks * 2 phases * 0.3s = 1.2s)
-    clock.update(101.2, False)
-    assert clock.state == wecker.STATE_WAIT_FOR_INPUT
-    mock_gpio.output.assert_called_with(wecker.LED_PIN, mock_gpio.HIGH)
-
-
-def test_blinking_updates_time_correctly(mock_gpio, mock_pygame):
-    clock = wecker.AlarmClock()
-    clock.state = wecker.STATE_BLINKING
-    clock.target_blinks = 4
-
-    # Start blinking, then advance to the end of the sequence.
-    # 4 blinks * 2 phases * 0.3s = 2.4s
-    clock.update(100.0, False)
-    clock.update(102.4, False)
-
-    assert clock.state == wecker.STATE_WAIT_FOR_INPUT
-    assert clock.last_interaction_time == 102.4
+    get_style.assert_called_once_with("whatever")
+    fake_style_cls.assert_called_once_with(wecker.set_led)
+    fake.update.assert_called()
 
 
 def test_setup_uses_env_music_file(mock_gpio, mock_pygame, monkeypatch):