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

CHANGELOG.md

@@ -62,6 +62,20 @@ release that ships it.
   MiLB events synthesized from the MLB Stats API do not, so the lookup raised
   a bare `KeyError`. It now reads the already-validated competition-level
   status.
+- `SportsLive._is_game_really_over` no longer crashes the live-update pass when
+  a feed sends an explicit null `period`. `None >= FINAL_PERIOD` raised
+  `TypeError`, and the only caller (`_detect_stale_games`) has no `try/except`
+  — the same failure shape as the already-fixed null `period_text`.
+- An expired clock spelled `"00:00"` now ends the game. The check compared the
+  colon-stripped clock against a hand-listed set of literals, which `"0000"` is
+  not a member of, so a finished game with a two-digit-minute clock stayed on
+  the scoreboard indefinitely. The comparison is now numeric.
+- `SportsCore._load_fonts` resolves `assets/fonts` through the `_font_root()`
+  seam instead of the process working directory. Started outside the install
+  root, every scoreboard font silently degraded to PIL's default bitmap face.
+- `SportsCore._should_log` no longer raises `AttributeError` on the first
+  warning of a run; `_last_warning_time` is initialized in `__init__` rather
+  than lazily by an unrelated method.
 - `SportsCore._resolve_project_path` resolved relative logo directories
   against `<root>/src` instead of the repo root after `sports.py` became a
   package — the class bodies moved byte-identically but `__file__` gained a