Fix composite margin ratio cap at 50% and add risk guide page with nav toggle.

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

app.py

@@ -231,6 +231,7 @@ def _static_asset_v() -> str:
         "static/css/responsive.css",
         "static/css/trade.css",
         "static/css/dashboard.css",
+        "static/css/doc.css",
         "static/css/base.css",
     )
     mtimes = []
@@ -1644,6 +1645,20 @@ def dashboard():
     return render_template("dashboard.html")
 
 
+@app.route("/risk-guide")
+@login_required
+@require_nav("risk_guide")
+def risk_guide():
+    from doc_render import read_doc, render_markdown
+
+    try:
+        _title, raw = read_doc("risk-guide")
+    except FileNotFoundError:
+        flash("文档不存在")
+        return redirect(url_for("positions"))
+    return render_template("risk_guide.html", doc_html=render_markdown(raw))
+
+
 @app.route("/api/dashboard/live")
 @login_required
 def api_dashboard_live():