Fix rainbow pattern step range in lighting controller

- Change step calculation from beat_index % 2 to beat_index % 256
- Provides full 0-255 step range for rainbow pattern color cycling
- Fixes rainbow pattern that was limited to only 0 or 1 step values
- Alternating phase patterns still use % 2 for proper phase offset

src/midi.py

@@ -152,7 +152,7 @@ class MidiHandler:
                 "n1": self.n1,
                 "n2": self.n2,
                 "n3": self.n3,
-                "s": self.beat_index % 2,  # Keep step small (0 or 1) for alternating patterns
+                "s": self.beat_index % 256,  # Use full range for rainbow patterns
             }
         }
         
@@ -233,7 +233,7 @@ class MidiHandler:
                 "n2": self.n2,
                 "n3": self.n3,
                 "dl": self.delay,
-                "s": self.beat_index % 2,  # Keep step small (0 or 1) for alternating patterns
+                "s": self.beat_index % 256,  # Use full range for rainbow patterns
             })
         
         # Add empty entries for each bar (they'll use defaults)