Add segmented_movement pattern with alternating forward/backward movement

- Add n4 parameter support to main.py ESP NOW receiver
- Implement segmented_movement pattern with configurable parameters:
  * n1: segment length (number of LEDs per segment)
  * n2: spacing between segments
  * n3: forward movement speed (positions per beat)
  * n4: backward movement speed (positions per beat)
- Pattern alternates between forward and backward movement each beat
- If only n3 or n4 is set, moves in that direction every beat
- Draws repeating segments with spacing across entire LED strip
- Add Pipfile script to run dev.py directly with arguments

Pipfile

@@ -16,4 +16,4 @@ uvicorn = "*"
 python_version = "3.12"
 
 [scripts]
-dev = 'watchfiles "./dev.py /dev/ttyACM0 src reset follow"'
+dev = "./dev.py"