fix(patterns): correct non-blocking timing and blink off phase

Co-authored-by: Cursor <cursoragent@cursor.com>

src/patterns/pulse.py

@@ -18,6 +18,7 @@ class Pulse:
 
         # State machine based pulse using a single generator loop
         while True:
+            bg_color = self.driver.apply_brightness(colors[-1], preset.b)
             # Read current timing parameters from preset
             attack_ms = max(0, int(preset.n1))  # Attack time in ms
             hold_ms = max(0, int(preset.n2))    # Hold time in ms
@@ -49,7 +50,7 @@ class Pulse:
                 self.driver.fill(self.driver.apply_brightness(color, preset.b))
             elif elapsed < total_ms:
                 # Delay phase: LEDs off between pulses
-                self.driver.fill((0, 0, 0))
+                self.driver.fill(bg_color)
             else:
                 # End of cycle, move to next color and restart timing
                 color_index += 1