优化中控科技风界面：登录居中、浮盈配色、默认打开首个客户端。

总览改名期权持仓总览，内容区 1800 居中，去掉左上角仓库名。

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

app.py

@@ -91,13 +91,13 @@ def login():
         if u == hub_username() and p == hub_password():
             session["logged_in"] = True
             session.permanent = True
-            nxt = (request.args.get("next") or request.form.get("next") or "/").strip() or "/"
+            nxt = (request.args.get("next") or request.form.get("next") or "/desk").strip() or "/desk"
             if not nxt.startswith("/"):
-                nxt = "/"
+                nxt = "/desk"
             return redirect(nxt)
         flash("用户名或密码错误")
     if session.get("logged_in"):
-        return redirect("/")
+        return redirect("/desk")
     return render_template("login.html")
 
 
@@ -195,7 +195,11 @@ def settings_page():
 @app.route("/desk")
 @login_required
 def desk():
+    instances = list_instances(enabled_only=True)
     iid = request.args.get("id")
+    # 未指定客户端时默认打开第一个
+    if (not iid or not str(iid).isdigit()) and instances:
+        return redirect(url_for("desk", id=instances[0]["id"]))
     inst = None
     open_url = ""
     if iid and str(iid).isdigit():
@@ -209,7 +213,7 @@ def desk():
             )
     return render_template(
         "desk.html",
-        instances=list_instances(enabled_only=True),
+        instances=instances,
         current=inst,
         open_url=open_url,
     )