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

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

src/patterns/bar_graph.py

@@ -16,7 +16,7 @@ class BarGraph:
                 target = (self.driver.num_leds * level) // 100
                 lit = self.driver.apply_brightness(colors[0], preset.b)
                 unlit = self.driver.apply_brightness(
-                    colors[1] if len(colors) > 1 else (0, 0, 0),
+                    colors[-1],
                     preset.b,
                 )
                 for i in range(self.driver.num_leds):