add toc, markdown jump, default docs

frontend/src/styles.css

@@ -566,7 +566,7 @@ html, body, #root {
   position: fixed;
   top: 60px;
   right: 20px;
-  width: 420px;
+  width: 620px;
   max-height: calc(100vh - 80px);
   background: #1e293b;
   border: 1px solid #334155;
@@ -700,6 +700,82 @@ html, body, #root {
 
 .node-help-panel-body strong { color: #e2e8f0; }
 
+/* ── Help panel TOC + content layout ──────────────────────────────── */
+
+.help-content-row {
+  display: flex;
+  flex: 1;
+  min-height: 0;
+  overflow: hidden;
+}
+
+.help-content-row > .node-help-panel-body {
+  flex: 1;
+  min-width: 0;
+}
+
+.help-toc {
+  width: 160px;
+  flex-shrink: 0;
+  overflow-y: auto;
+  border-right: 1px solid #1e293b;
+  padding: 8px 0;
+  font-size: 11px;
+  background: #0f172a;
+}
+
+.help-toc-root { padding: 0; }
+
+.help-toc-list {
+  list-style: none;
+  margin: 0;
+  padding: 0 0 0 10px;
+}
+
+.help-toc-item {
+  margin: 0;
+}
+
+.help-toc-row {
+  display: flex;
+  align-items: baseline;
+  gap: 2px;
+}
+
+.help-toc-arrow {
+  background: none;
+  border: none;
+  color: #475569;
+  font-size: 7px;
+  padding: 0;
+  width: 12px;
+  flex-shrink: 0;
+  cursor: pointer;
+  text-align: center;
+  line-height: 1;
+  transition: color 0.12s;
+}
+.help-toc-arrow:hover { color: #94a3b8; }
+
+.help-toc-arrow-spacer {
+  display: inline-block;
+  width: 12px;
+  flex-shrink: 0;
+}
+
+.help-toc-link {
+  color: #94a3b8;
+  text-decoration: none;
+  padding: 2px 6px 2px 0;
+  display: block;
+  line-height: 1.4;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  transition: color 0.12s;
+}
+.help-toc-link:hover { color: #f1f5f9; }
+
 .node-body {
   padding: 4px 0;
   display: flex;