feat: P0-02/P0-03/P0-05 数据库时间语义与约束

P0-02: MatchStats 增加 source/source_record_id/retrieved_at/available_at
        context_builder 过滤统计数据时检查 available_at <= cutoff
P0-03: Prediction 增加 match_kickoff_at/prediction_created_at/prediction_cutoff_at
        明确区分比赛时间/预测创建时间/数据截止时间
P0-05: Prediction 增加 status 字段(success/failed/degraded)
        数据库 CHECK 约束

Alembic: 0005_prediction_status_and_stats_provenance

P1-02: injuries as_of 不再截断为 date,保持 datetime 精度

src/llm/agents/orchestrator.py

@@ -7,6 +7,7 @@ import json
 import logging
 import time
 from dataclasses import dataclass
+from datetime import datetime, timezone
 
 from src.core.config import settings
 from src.db.base import AsyncSessionLocal
@@ -166,7 +167,9 @@ async def predict_match_multi(
 
     # 1. 比赛头(各 agent 共享;不存在则 404)
     header = await load_match_header(match_id)
-    cutoff_at = header.match_dt
+    match_kickoff_at = header.match_dt
+    prediction_cutoff_at = header.match_dt  # 默认:比赛时间作为数据截止
+    now = datetime.now(timezone.utc)
 
     # 2. 并行专家
     specialist_provider = _get_specialist_provider()
@@ -215,7 +218,10 @@ async def predict_match_multi(
             reasoning=validated.reasoning,
             raw_response=final,
             agent_outputs=[r.to_dict() for r in reports],
-            cutoff_at=cutoff_at,
+            status="success",
+            match_kickoff_at=match_kickoff_at,
+            prediction_cutoff_at=prediction_cutoff_at,
+            prediction_created_at=now,
             input_hash=input_hash,
         )
         session.add(pred)