chore: 死代码与重复逻辑清理

删除未引用/未调用符号:
- PredictionRepository(无引用)
- is_correct_1x2(无调用者)
- LeagueOut(路由用 list[dict])
- IngestResponse(IngestBzzoiroResponse 已替代)
- SecurityCheckError(从未 raise,assert_security_on_startup 用 sys.exit)
- short_write(仅自引用,全仓库无外部调用)
- fetchIngestJobs(列表函数无页面使用,单数 fetchIngestJob 仍保留)
- clear_prompt_cache(无入口)

去重:
- eval._actual_1x2 改为委托 utils.actual_1x2(单一权威源)

全量测试 270 通过,业务行为不变。

src/llm/eval.py

@@ -7,6 +7,7 @@ from sqlalchemy import func, or_, select
 
 from src.db.models import Prediction, Match, League
 from src.db.unit_of_work import get_uow
+from src.llm.utils import actual_1x2
 
 logger = logging.getLogger(__name__)
 
@@ -33,12 +34,8 @@ async def settle_prediction(prediction_id: int, home_goals: int, away_goals: int
 
 
 def _actual_1x2(home: int, away: int) -> str:
-    """根据实际比分返胜平负。"""
-    if home > away:
-        return "1"
-    if home == away:
-        return "X"
-    return "2"
+    """根据实际比分返胜平负(委托 utils.actual_1x2 单一权威源)。"""
+    return actual_1x2(home, away)
 
 
 def _build_filters(