Refine calibration, chase, and spin patterns and add spin test

Increase calibration brightness, update chase to use the new logical ring abstraction, and make spin start from a cleared frame with symmetric arm speed, alongside a dedicated on-device spin test script.

Made-with: Cursor

pico/src/patterns/calibration.py

@@ -1,6 +1,6 @@
 """Calibration: strips 2 and 6 only. First 10 green, then alternating 10 blue / 10 red. 10% brightness."""
 
-BRIGHTNESS = 0.10
+BRIGHTNESS = 1
 BLOCK = 10
 STRIPS_ON = (2, 6)  # 0-based: 3rd and 7th strip only
 
@@ -22,6 +22,7 @@ class Calibration:
         green = _scale(GREEN, BRIGHTNESS)
         red = _scale(RED, BRIGHTNESS)
         blue = _scale(BLUE, BRIGHTNESS)
+        blue = (0,0,0)
         on_set = set(STRIPS_ON)
         for strip_idx, strip in enumerate(strips):
             n = strip.num_leds