fix(sports): harden the live game-over check and font/log init

Follow-up review findings on the promoted base-class methods.

_is_game_really_over:
- `period` present-but-None raised TypeError on `None >= FINAL_PERIOD`,
  taking down the whole live-update pass (_detect_stale_games has no
  try/except). Same failure shape as the null `period_text` already fixed.
- An expired clock spelled "00:00" normalizes to "0000", which matched
  none of the hand-listed literals, so a finished game with a two-digit
  minute clock stayed on the scoreboard forever. Compare numerically.

SportsCore:
- _load_fonts kept the cwd-relative "assets/fonts/..." literals the
  _font_root() seam exists to remove, so every scoreboard font degraded
  to PIL's default face outside the install root.
- _should_log read self._last_warning_time unguarded while only an
  unrelated method initialized it lazily; the first warning of a run
  raised AttributeError. Initialize it in __init__.

Also documents that game_update_timestamps is written by subclasses, not
by the base class, so the staleness branch is inert until B5 adoption.

14 new tests. Gates: 463 core unit, 60 plugin safety.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FgbA8SMutQQpXkMG8LMmC4

test/test_sports_core_promotions.py

@@ -465,6 +465,38 @@ class TestFontLoaderCwdIndependence:
         assert isinstance(font, ImageFont.FreeTypeFont)
         assert Path(font.path) == FONTS_DIR / TTF_NAME
 
+    @pytest.mark.parametrize("key", ["score", "time", "team", "status",
+                                     "detail", "rank"])
+    def test_load_fonts_survives_an_unrelated_cwd(self, monkeypatch, key):
+        """`_load_fonts` had the same cwd-relative literals the seam exists to
+        remove; every scoreboard font silently became PIL's default bitmap face
+        when the process started outside the install root."""
+        monkeypatch.chdir("/")
+        fonts = SportsCore._load_fonts(probe())
+        assert isinstance(fonts[key], ImageFont.FreeTypeFont), (
+            f"fonts['{key}'] degraded to PIL's default face outside the "
+            "install root")
+
+
+class TestShouldLogCooldown:
+    """`_should_log` reads `self._last_warning_time` unguarded, so it must be
+    initialized in __init__ — otherwise the first warning of a run raises
+    AttributeError instead of logging."""
+
+    def test_cooldown_clock_is_initialized(self, build):
+        assert build()._last_warning_time == 0
+
+    def test_first_call_logs_then_cools_down(self, build):
+        manager = build()
+        assert manager._should_log("api", cooldown=60) is True
+        assert manager._should_log("api", cooldown=60) is False
+
+    def test_cooldown_expires(self, build):
+        manager = build()
+        assert manager._should_log("api", cooldown=60) is True
+        manager._last_warning_time -= 61
+        assert manager._should_log("api", cooldown=60) is True
+
 
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 # 4. Seam guard rails