feat(theme): add brown and orange background gradients

src/foundation/foundation.css

@@ -35,4 +35,6 @@
 .hm-foundation .hm-color-gradient-preview { height: 112px; }
 .hm-foundation .hm-color-gradient-stops { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 16px; }
 .hm-foundation .hm-color-gradient-stops .hm-brand-color-chip { flex: 1 1 110px; }
+/* New common background stop IDs stay on one line at the supported widths. */
+.hm-foundation .hm-color-gradient-stops .hm-brand-color-chip[data-gradient-stop-token] { flex-basis: 220px; }
 .hm-foundation .hm-color-foreground-sample { padding: 16px; background: var(--hm-sem-bg-surface); }