feat: 核心股追踪行点击展开显示所属题材列表

- active 接口返回每只核心股 themes(窗口内按题材去重)
- 页面行点击展开题材标签,chevron 指示展开状态

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

backend/routes/core_stocks.py

@@ -59,6 +59,19 @@ async def active_core_stocks():
         stocks.sort(key=lambda x: x.get("lastAppear") or "", reverse=True)
         stocks.sort(key=lambda x: -x["appearCount"])
 
+        # 一次性取窗口内全部题材关联，按 stock_code 分组（跨天题材去重）
+        themes_rows = conn.execute(
+            f"""SELECT stock_code, theme_code, theme_name FROM daily_core_stock_themes
+                WHERE trade_date IN ({placeholders})""",
+            dates,
+        ).fetchall()
+        themes_by_stock: dict[str, dict[str, dict]] = {}
+        for t in themes_rows:
+            per = themes_by_stock.setdefault(t["stock_code"], {})
+            per.setdefault(t["theme_code"], {"theme_code": t["theme_code"], "theme_name": t["theme_name"]})
+        for s in stocks:
+            s["themes"] = list(themes_by_stock.get(s["stockCode"], {}).values())
+
         # daysSinceLastAppear:最近上榜距窗口最新交易日的自然日差(简单口径)
         latest = dates[-1] if dates else None
         for s in stocks: