fix(sports): let the plugin declare its own directory, don't deduce it (#519)

_plugin_dir() returned None on every device. The consequence was silent and
reached the panel:

    _plugin_dir()       -> None
    _schema_font_size() -> None for every element
    -> a configured size equal to the schema default stops looking like a
       default and is treated as a deliberate user choice
    -> the snap to the font's pixel grid is skipped
    -> 4x6-font.ttf renders at 6 instead of 7: 3px-wide glyphs, not 4px

On a 256x64 panel that made the odds, the team records and the date row hard to
read. Both `odds` and `detail` were affected -- anything resolving a
grid-snapped schema default was a pixel narrow.

Why it was invisible here. PluginLoader._namespace_plugin_modules renames every
bare module a plugin brought in (sports, game_renderer, ...) to
"_plg_<plugin_id>_<module>" and REMOVES the bare sys.modules entry, so two
plugins owning a module of the same name cannot collide. A class defined in
sports.py still reports __module__ == "sports", but sys.modules["sports"] is
gone, so walking the MRO for a module with a __file__ finds nothing.

Every test here imported plugins directly, which leaves the bare entry in
place, so the walk succeeded. The safety harness loads plugins its own way and
never reproduced it either. It was found by a user counting pixels on the
panel.

The directory is now declared by the plugin (_PLUGIN_DIR) and only deduced as
a fallback, for hosts that declare nothing -- the plugins' own probe harnesses
build classes with type().

Verified on hardware, which is the only place the original failure appeared:
before, the live service logged plugin_dir=None and 4x6-font.ttf@6 for all six
football managers; after, plugin_dir resolves and both odds and detail are @7.

Five regression tests, including the production shape: a class whose __module__
is absent from sys.modules still resolves via its declared directory, and the
precondition that the MRO walk alone returns None is pinned so the test keeps
meaning something if the fallback changes.

test/test_sports_shared.py

@@ -319,3 +319,58 @@ class TestLiveMixin:
         assert not hasattr(h, "_empty_live_streak")
         h._note_live_fetch(False)
         assert h._empty_live_streak == 1
+
+
+class TestPluginDirIsToldNotDeduced:
+    """The regression that shipped: _plugin_dir returned None in production.
+
+    The first version walked the MRO for a class whose module sits beside a
+    config_schema.json. That passes when a test imports the plugin directly --
+    which is how it was verified -- and returns None under the real plugin
+    loader, which imports modules by a path that leaves no such entry on the
+    MRO.
+
+    Silent, and expensive: no schema means _schema_font_size returns None for
+    every element, so a configured size equal to the schema default stops
+    looking like a default, is treated as a deliberate choice, and skips the
+    grid snap. 4x6-font.ttf then renders at 6 rather than 7 -- 3px-wide glyphs
+    instead of 4px. On a 256x64 panel that made the odds, the records and the
+    date row illegible. A user counted the pixels; no gate here caught it.
+    """
+
+    def test_a_declared_directory_is_used(self, tmp_path):
+        d = _write_plugin(tmp_path, "declared")
+        host = type("H", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(d)})()
+        assert host._plugin_dir() == str(d)
+
+    def test_it_works_when_no_module_on_the_mro_helps(self, tmp_path, monkeypatch):
+        """The production case: nothing on the MRO sits beside a schema."""
+        d = _write_plugin(tmp_path, "loaderstyle")
+        # A class whose module is not importable by name, as the loader produces.
+        cls = type("Loaded", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(d)})
+        cls.__module__ = "a.module.name.that.is.not.in.sys.modules"
+        assert cls.__new__(cls)._plugin_dir() == str(d), (
+            "the declared directory must win when the MRO walk cannot help")
+
+    def test_without_it_the_mro_walk_would_have_failed(self):
+        # Pin the precondition, so this test still means something if the
+        # fallback is ever changed.
+        cls = type("Orphan", (SportsCoreSharedMixin,), {})
+        cls.__module__ = "not.a.real.module"
+        assert cls.__new__(cls)._plugin_dir() is None
+
+    def test_a_declared_directory_without_a_schema_is_not_trusted(self, tmp_path):
+        # A stale or wrong path must not shadow the fallback.
+        empty = tmp_path / "noschema"
+        empty.mkdir()
+        d = _write_plugin(tmp_path, "realone")
+        monkey = type("H", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(empty)})
+        assert monkey.__new__(monkey)._plugin_dir() != str(empty)
+
+    def test_the_font_size_consequence(self, tmp_path):
+        """End to end: a declared directory restores the schema lookup."""
+        d = _write_plugin(tmp_path, "sizeconseq")
+        host = type("H", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(d)})()
+        assert host._schema_font_size("score") == 16, (
+            "without the schema this is None, which is what made a configured "
+            "size look user-chosen and skipped the grid snap")