Add per-card save and collapse on settings page

Each settings section and exchange card gets its own save button and fold toggle with state persisted in localStorage.

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

manual_trading_hub/static/app.css

@@ -2642,8 +2642,168 @@ button.btn-sm {
 .settings-display-panel,
 .settings-macro-panel,
 .settings-supervisor-panel {
+  margin-bottom: 0;
+}
+
+.settings-section {
   margin-bottom: 16px;
+}
+
+.settings-section-head {
+  display: flex;
+  align-items: center;
+  gap: 10px;
   padding: 14px 16px;
+  border-bottom: 1px solid var(--border-soft);
+}
+
+.settings-section.is-collapsed .settings-section-head {
+  border-bottom-color: transparent;
+}
+
+.settings-section-head .settings-display-title {
+  flex: 1;
+  margin: 0;
+  min-width: 0;
+}
+
+.settings-section-head-actions {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  flex-shrink: 0;
+}
+
+.settings-section-fold {
+  flex-shrink: 0;
+  width: 28px;
+  height: 28px;
+  padding: 0;
+  border: 1px solid var(--border-soft);
+  border-radius: 6px;
+  background: color-mix(in srgb, var(--panel) 90%, var(--accent) 10%);
+  color: var(--accent);
+  cursor: pointer;
+  font-size: 0;
+  line-height: 1;
+  transition: transform 0.15s ease, border-color 0.15s ease;
+  position: relative;
+}
+
+.settings-section-fold::before {
+  content: "▾";
+  font-size: 0.85rem;
+  line-height: 28px;
+  display: block;
+  text-align: center;
+}
+
+.settings-section-fold:hover {
+  border-color: color-mix(in srgb, var(--accent) 50%, var(--border-soft));
+}
+
+.settings-section.is-collapsed .settings-section-fold::before {
+  content: "▸";
+}
+
+.settings-section-save {
+  flex-shrink: 0;
+  font-size: 0.82rem;
+  padding: 6px 14px;
+}
+
+.settings-section-body {
+  padding: 14px 16px;
+}
+
+.settings-section.is-collapsed .settings-section-body {
+  display: none;
+}
+
+.settings-page-toolbar {
+  margin-top: 4px;
+}
+
+.settings-card-topbar {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-bottom: 12px;
+  padding-bottom: 10px;
+  border-bottom: 1px dashed var(--border-soft);
+}
+
+.settings-card-fold {
+  flex-shrink: 0;
+  width: 26px;
+  height: 26px;
+  padding: 0;
+  border: 1px solid var(--border-soft);
+  border-radius: 6px;
+  background: transparent;
+  color: var(--muted);
+  cursor: pointer;
+  font-size: 0;
+  line-height: 1;
+  transition: color 0.15s ease, border-color 0.15s ease;
+  position: relative;
+}
+
+.settings-card-fold::before {
+  content: "▾";
+  font-size: 0.8rem;
+  line-height: 26px;
+  display: block;
+  text-align: center;
+}
+
+.settings-card-fold:hover {
+  color: var(--accent);
+  border-color: color-mix(in srgb, var(--accent) 40%, var(--border-soft));
+}
+
+.settings-card.is-collapsed .settings-card-fold::before {
+  content: "▸";
+}
+
+.settings-card-title {
+  flex: 1;
+  min-width: 0;
+  font-size: 0.92rem;
+  font-weight: 600;
+  color: var(--text);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+
+.settings-card-save {
+  flex-shrink: 0;
+  font-size: 0.78rem;
+  padding: 5px 12px;
+}
+
+.settings-card-body {
+  display: block;
+}
+
+.settings-card.is-collapsed .settings-card-body {
+  display: none;
+}
+
+@media (max-width: 720px) {
+  .settings-section-head {
+    flex-wrap: wrap;
+  }
+
+  .settings-section-head-actions {
+    width: 100%;
+    justify-content: flex-end;
+  }
+
+  .settings-card-topbar {
+    flex-wrap: wrap;
+  }
 }
 
 .settings-display-title {