Add global brightness support to driver

Handle per-device global brightness via ESPNow messages and apply it alongside per-preset brightness in all patterns.

src/main.py

@@ -28,9 +28,16 @@ while True:
     if e.any():
         host, msg = e.recv()
         data = json.loads(msg)
-        if data["v"] != "1":
+        # Only handle messages with the expected version.
+        if data.get("v") != "1":
             continue
         print(data)
+        # Global brightness (0–255) for this device
+        if "b" in data:
+            try:
+                patterns.b = max(0, min(255, int(data["b"])))
+            except (TypeError, ValueError):
+                pass
         if "presets" in data:
             for name, preset_data in data["presets"].items():
                 # Convert hex color strings to RGB tuples and reorder based on device color order
@@ -44,4 +51,3 @@ while True:
                 preset_name = select_list[0]
                 step = select_list[1] if len(select_list) > 1 else None
                 patterns.select(preset_name, step=step)
-