feat: 数据采集健壮性改进

- 新增 src/core/retry.py: 指数退避 + 抖动的重试装饰器
- bzzoiro: 改进重试逻辑
  - 429/5xx/网络错误均触发指数退避重试
  - 4xx 直接抛(不重试)
- understat: 新增重试(原无重试)
- injuries: 新增重试 + 文件缓存 7 天过期
- sources.py: 延迟导入修复循环导入

src/data/injuries.py

@@ -4,8 +4,11 @@
 """
 from __future__ import annotations
 
+import asyncio
 import json
 import logging
+import random
+import time
 from datetime import datetime, timezone
 from pathlib import Path
 from typing import Any
@@ -42,13 +45,17 @@ async def fetch_injuries(*, date: str | None = None, fixture_id: int | None = No
     cache_dir = _CACHE_DIR
     cache_dir.mkdir(parents=True, exist_ok=True)
 
-    # 缓存命中
+    # 缓存命中 (7 天内有效)
     cache_key = f"injuries_{date}_{fixture_id}_{league_id}.json"
     cache_file = cache_dir / cache_key
     if cache_file.exists():
-        logger.debug("injuries cache hit: %s", cache_key)
-        with open(cache_file, encoding="utf-8") as f:
-            return json.load(f)
+        age_hours = (time.time() - cache_file.stat().st_mtime) / 3600
+        if age_hours < 168:  # 7 天
+            logger.debug("injuries cache hit: %s (%.1fh old)", cache_key, age_hours)
+            with open(cache_file, encoding="utf-8") as f:
+                return json.load(f)
+        else:
+            logger.debug("injuries cache expired: %s (%.1fh old)", cache_key, age_hours)
 
     headers = {
         "x-apisports-key": api_key,
@@ -63,11 +70,26 @@ async def fetch_injuries(*, date: str | None = None, fixture_id: int | None = No
         params["league"] = league_id
 
     url = f"{API_BASE}/injuries"
-    client = get_client()
-    resp = await client.get(url, headers=headers, params=params)
-    resp.raise_for_status()
-    data = resp.json()
 
+    # 重试
+    last_exc: Exception | None = None
+    for attempt in range(3):
+        try:
+            client = get_client()
+            resp = await client.get(url, headers=headers, params=params, timeout=30)
+            resp.raise_for_status()
+            break
+        except Exception as e:
+            last_exc = e
+            if attempt == 2:
+                raise
+            delay = min(2 ** attempt, 8) + random.uniform(0, 1)
+            logger.warning("injuries fetch failed, retry %d in %.1fs: %s", attempt + 1, delay, e)
+            await asyncio.sleep(delay)
+    else:
+        raise RuntimeError(f"injuries fetch failed: {last_exc}")
+
+    data = resp.json()
     injuries = data.get("response", [])
 
     # 写缓存