feat(zones): profile-scoped groups, zone modes, sequence brightness

- Optional profile_id on groups; UI and API for shared vs profile-only groups\n- Zone content_kind (presets vs sequences); edit modal shows matching sections; devices via groups only\n- Server sequence playback folds zone brightness into preset wire b (per MAC where needed)\n- Related preset/sequence/audio/beat-route and client updates

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

src/util/espnow_message.py

@@ -78,13 +78,49 @@ def build_select_message(device_name, preset_name, step=None):
     return {device_name: select_list}
 
 
-def build_preset_dict(preset_data):
+def _hex_from_background_raw(bg_raw):
+    """Coerce ``background`` / ``bg`` field to a ``#RRGGBB`` string (driver wire format)."""
+    if isinstance(bg_raw, str):
+        bg = bg_raw if bg_raw.startswith("#") else f"#{bg_raw}"
+        return bg
+    if isinstance(bg_raw, (list, tuple)) and len(bg_raw) == 3:
+        return f"#{int(bg_raw[0]):02x}{int(bg_raw[1]):02x}{int(bg_raw[2]):02x}"
+    return "#000000"
+
+
+def resolve_preset_background_hex(preset_data, palette_colors=None):
+    """
+    Resolved background as ``#RRGGBB``. When ``palette_colors`` is a non-empty list and
+    ``background_palette_ref`` is set, uses that palette index; otherwise stored ``background`` / ``bg``.
+    """
+    if not isinstance(preset_data, dict):
+        return "#000000"
+    pal = list(palette_colors) if isinstance(palette_colors, list) else []
+    ref = preset_data.get("background_palette_ref", preset_data.get("backgroundPaletteRef"))
+    if pal and ref is not None:
+        try:
+            idx = int(ref)
+        except (TypeError, ValueError):
+            idx = None
+        else:
+            if isinstance(idx, int) and 0 <= idx < len(pal):
+                c = pal[idx]
+                if isinstance(c, str) and c.strip().startswith("#"):
+                    s = c.strip()
+                    if len(s) == 7 and all(ch in "0123456789abcdefABCDEF" for ch in s[1:]):
+                        return s.upper()
+    bg_raw = preset_data.get("background", preset_data.get("bg", "#000000"))
+    return _hex_from_background_raw(bg_raw)
+
+
+def build_preset_dict(preset_data, palette_colors=None):
     """
     Convert preset data to API-compliant format.
     
     Args:
         preset_data: Dictionary with preset fields (may include name, pattern, colors, etc.)
-        
+        palette_colors: Optional list of ``#RRGGBB`` strings for ``background_palette_ref`` resolution.
+
     Returns:
         Dictionary with preset in API-compliant format (without name field)
         
@@ -137,13 +173,7 @@ def build_preset_dict(preset_data):
     auto_raw = preset_data.get("auto", preset_data.get("a", True))
     auto_bool = _coerce_auto(auto_raw)
 
-    bg_raw = preset_data.get("background", preset_data.get("bg", "#000000"))
-    if isinstance(bg_raw, str):
-        bg = bg_raw if bg_raw.startswith("#") else f"#{bg_raw}"
-    elif isinstance(bg_raw, (list, tuple)) and len(bg_raw) == 3:
-        bg = f"#{int(bg_raw[0]):02x}{int(bg_raw[1]):02x}{int(bg_raw[2]):02x}"
-    else:
-        bg = "#000000"
+    bg = resolve_preset_background_hex(preset_data, palette_colors)
 
     # Build payload using the short keys expected by led-driver
     preset = {
@@ -164,13 +194,14 @@ def build_preset_dict(preset_data):
     return preset
 
 
-def build_presets_dict(presets_data):
+def build_presets_dict(presets_data, palette_colors=None):
     """
     Convert multiple presets to API-compliant format.
     
     Args:
         presets_data: Dictionary mapping preset names to preset data
-        
+        palette_colors: Optional list of ``#RRGGBB`` strings for background palette ref resolution.
+
     Returns:
         Dictionary mapping preset names to API-compliant preset objects
         
@@ -190,7 +221,7 @@ def build_presets_dict(presets_data):
     """
     result = {}
     for preset_name, preset_data in presets_data.items():
-        result[preset_name] = build_preset_dict(preset_data)
+        result[preset_name] = build_preset_dict(preset_data, palette_colors)
     return result