refactor(sports): one reader for element colours and layout offsets

There were two copies of the per-element colour read and three of the
layout-offset read. They had already drifted -- the scroll-card renderer
carries a comment about having ignored offsets its own schema advertised
-- and each new capability had to be added to all of them or silently work
in some places and not others.

All of them now go through src.element_style, which is what carries the
alias handling and the per-mode lookup. That lands immediately for the
nine plugins importing these modules: a scoreboard asking for `score_text`
offsets finds the `layout.score` its users configured, and a Live instance
resolves its own colours through SKIN_MODE without any call site passing a
mode.

_normalize_color learned "#RRGGBB" in the process. The scoreboards' own
readers have always accepted it, so the shared one had to, or consolidating
would have quietly dropped a form users' configs may hold. _coerce_offset
picked up the non-finite guard the scroll-card reader had and the other two
did not.

_get_layout_offset is promoted onto SportsCoreSharedMixin. Each plugin
still carries its own copy in its bundled sports.py, which wins by MRO --
so adopting this is a deletion in the plugin, and until that deletion
nothing changes for it.

Note for whoever runs the suite next: test_display_dirty_tracking.py is
order-dependent. Fifteen of its tests failed in one full run and passed in
the next with no change in between, and pass in isolation. Pre-existing,
unrelated to this, but it makes a full-run diff untrustworthy until it is
fixed.

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

test/test_sports_shared.py

@@ -422,3 +422,43 @@ class TestUnshareKeepsTheLayoutEngine:
         fonts = {"score": shared, "time": shared}
         self._host()._unshare_element_fonts(fonts)
         assert fonts["time"].getlength("88-88") == shared.getlength("88-88")
+
+
+class TestPromotedLayoutOffset:
+    """_get_layout_offset moved here so every scoreboard reads offsets the
+    way the scroll card does.
+
+    Each plugin still carries its own copy in its bundled sports.py, which
+    wins by MRO. That is the migration property: adopting this is a
+    deletion in the plugin, and until that deletion nothing changes.
+    """
+
+    CONFIG = {"customization": {
+        "layout": {"score": {"y_offset": -3}},
+        "modes": {"recent": {"layout": {"score": {"y_offset": 9}}}},
+    }}
+
+    def _host(self, **attrs):
+        return type("H", (SportsCoreSharedMixin,),
+                    dict({"config": self.CONFIG}, **attrs))()
+
+    def test_it_reads_the_configured_offset(self):
+        assert self._host()._get_layout_offset("score", "y_offset") == -3
+
+    def test_it_resolves_through_an_alias(self):
+        """What a plugin gains by deleting its own copy: the style block
+        says score_text where the layout block says score."""
+        assert self._host()._get_layout_offset("score_text", "y_offset") == -3
+
+    def test_skin_mode_selects_the_per_mode_offset(self):
+        assert self._host(SKIN_MODE="recent")._get_layout_offset(
+            "score", "y_offset") == 9
+
+    def test_a_plugins_own_copy_still_wins(self):
+        """Until a plugin deletes its copy, this changes nothing for it."""
+        host = self._host(
+            _get_layout_offset=lambda self, element, axis, default=0: 99)
+        assert host._get_layout_offset("score", "y_offset") == 99
+
+    def test_an_unset_offset_is_the_default(self):
+        assert self._host()._get_layout_offset("nothing", "y_offset", 5) == 5