Redesign roll calculator with auto first entry and chained add legs.

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

manual_trading_hub/static/app.css

@@ -6938,6 +6938,57 @@ body.funds-fullscreen-open {
   margin: 0;
 }
 
+.calc-roll-legs-head {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 10px;
+  margin: 14px 0 8px;
+  font-size: 0.82rem;
+  color: var(--text);
+}
+
+.calc-roll-legs-list {
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+}
+
+.calc-roll-leg {
+  border: 1px solid var(--border-soft);
+  border-radius: 8px;
+  padding: 10px 12px;
+  background: var(--bg-elevated);
+}
+
+.calc-roll-leg-title {
+  font-size: 0.8rem;
+  font-weight: 600;
+  color: var(--muted);
+  margin-bottom: 8px;
+}
+
+.calc-roll-leg-grid {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 10px;
+}
+
+.calc-roll-leg-remove {
+  margin-top: 8px;
+  font-size: 0.78rem;
+}
+
+.calc-done-tag {
+  display: inline-block;
+  margin-left: 6px;
+  padding: 1px 6px;
+  border-radius: 999px;
+  font-size: 0.68rem;
+  color: var(--muted);
+  border: 1px solid var(--border-soft);
+}
+
 @media (max-width: 960px) {
   .calc-layout {
     grid-template-columns: 1fr;