fix(element-style): clamp out-of-range colour components instead of rejecting

A regression this framework shipped. The eight scoreboards used to read their
colours through sports_card.coerce_rgb, which clamps; routing them through the
shared element_color sent them through _normalize_color, which rejected any
component outside 0..255 and fell back to the default. So a configured
[999, -5, 20] -- a typo'd bright red -- rendered white instead of (255, 0, 20).

Their own test_element_text_colors.py caught it: one case of nineteen, in all
eight plugins, failing only once the core change reached main.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/element_style.py

@@ -763,6 +763,12 @@ def _adopt_handwritten_block(schema: Dict[str, Any],
 
     for key in element_keys:
         _upgrade_font_property(props[key])
+        # Marked like a declared element, so consumers can tell the style
+        # blocks from whatever else the plugin keeps under customization.
+        # Football's block also holds favorite_result_colors, which is a
+        # feature with its own fields -- without this the editor treats it
+        # as an element and every row grows an "enabled"/"win color" column.
+        props[key]['x-style-managed'] = True
 
     modes = customization.get('x-style-modes')
     if isinstance(modes, list) and modes:
@@ -904,11 +910,14 @@ def _normalize_color(value: Any) -> Optional[Tuple[int, int, int]]:
         return None
     if isinstance(value, (list, tuple)) and len(value) == 3:
         try:
-            rgb = tuple(int(c) for c in value)
+            # Clamped, not rejected. The readers this replaced clamped
+            # (sports_card.coerce_rgb), and the eight scoreboards' own tests
+            # pin it: a configured [999, -5, 20] is a typo'd bright red, and
+            # answering "unusable, take the default" turned it white instead.
+            rgb = tuple(max(0, min(255, int(c))) for c in value)
         except (TypeError, ValueError):
             return None
-        if all(0 <= c <= 255 for c in rgb):
-            return rgb  # type: ignore[return-value]
+        return rgb  # type: ignore[return-value]
     return None