refactor: fix P0/P1/P2 security and performance issues

P0 fixes:
- CORS: replace wildcard methods/headers with configurable lists
- deps.py: remove unsafe global _warned_unset variable

P1 fixes:
- http_client: read default timeout from Settings
- bzzoiro: replace sync urllib with async httpx
- bzzoiro: normalize validation failures use warning level only
- db pool: read pool config from Settings (default 5+10)
- backtest: add asyncio.Semaphore(8) for concurrent execution
- predict/context_builder: add backtest parameter for cutoff buffer

P2 improvements:
- injuries: enforce int conversion for player_id/fixture_id
- injuries: use system temp dir for cache
- utils.py: extract shared actual_1x2/is_correct_1x2
- validation: downgrade 1x2 mismatch log to debug
- docker-compose: use env vars for all credentials
- .env.example: add POSTGRES_USER/PASSWORD/PORT, API_PORT

src/core/http_client.py

@@ -2,24 +2,27 @@
 
 使用方:
   - src/llm/provider.py: LLM 调用
+  - src/data/bzzoiro.py: bzzoiro 比赛数据
   - src/data/understat.py: xG 抓取
   - src/data/injuries.py: 伤停抓取
 
 生命周期由 FastAPI lifespan 管理(关闭时 aclose)。
+调用方可通过 `timeout` 参数覆盖 per-request 超时。
 """
 from __future__ import annotations
 
 import httpx
 
+from src.core.config import settings
+
 _shared_client: httpx.AsyncClient | None = None
-_default_timeout = 30
 
 
 def get_client() -> httpx.AsyncClient:
     """获取共享客户端(懒初始化)。"""
     global _shared_client
     if _shared_client is None or _shared_client.is_closed:
-        _shared_client = httpx.AsyncClient(timeout=_default_timeout)
+        _shared_client = httpx.AsyncClient(timeout=settings.HTTP_DEFAULT_TIMEOUT)
     return _shared_client