feat: add light/dark theme to exchange instances with hub SSO sync

Co-authored-by: Cursor <cursoragent@cursor.com>

manual_trading_hub/hub.py

@@ -1057,7 +1057,11 @@ def _require_hub_logged_in(request: Request) -> None:
 
 @app.get("/api/instance/open-url")
 def api_instance_open_url(
-    request: Request, exchange_id: str, next: str = "/", embed: str = ""
+    request: Request,
+    exchange_id: str,
+    next: str = "/",
+    embed: str = "",
+    hub_theme: str = "",
 ):
     """已登录中控时生成实例 SSO 打开链接（2h 有效、单次使用，复用 HUB_BRIDGE_TOKEN）。"""
     _require_hub_logged_in(request)
@@ -1079,6 +1083,9 @@ def api_instance_open_url(
     params = {"token": token, "next": nxt}
     if (embed or "").strip().lower() in ("1", "true", "yes", "on"):
         params["embed"] = "1"
+    ht = (hub_theme or "").strip().lower()
+    if ht in ("light", "dark"):
+        params["hub_theme"] = ht
     q = urlencode(params)
     return {
         "ok": True,