Include prediction result in cache endpoint response

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -321,6 +321,7 @@ async def get_cache(ts_code: str | None = None):
                 "cached_at":      entry["cached_at"].astimezone(_CST).strftime("%Y-%m-%d %H:%M:%S %Z"),
                 "expires_at":     entry["expires_at"].astimezone(_CST).strftime("%Y-%m-%d %H:%M:%S %Z"),
                 "ttl_seconds":    int(remaining),
+                "result":         entry["result"],
             })
     return {"count": len(entries), "entries": entries}