feat(zones): persist per-zone brightness and update submodules

Store zone brightness in model/data flow, apply it in the zones UI, and record updated led-driver, led-simulator, and led-tool submodule pointers.

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

src/models/zone.py

@@ -34,6 +34,7 @@ class Zone(Model):
             "names": names if names else [],
             "presets": presets if presets else [],
             "default_preset": None,
+            "brightness": 255,
         }
         self.save()
         return next_id