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

.env.example

@@ -3,6 +3,10 @@ APP_ENV=development
 LOG_LEVEL=INFO
 
 # ---- 数据库 ----
+POSTGRES_USER=football
+POSTGRES_PASSWORD=football
+POSTGRES_DB=football
+POSTGRES_PORT=5432
 DATABASE_URL=postgresql+asyncpg://football:football@localhost:5432/football
 
 # ---- LLM (OpenAI-compatible,必填一个) ----