feat(org-chart): add core cards and fixed-layout integration

examples/org-chart/p1.css

@@ -0,0 +1,12 @@
+/* Reuse the existing local variable font; only OrgChart selects this family. */
+@font-face {
+  font-family: 'Noto Sans KR';
+  src: url('./assets/fonts/NotoSansKR-variable.ttf') format('truetype');
+  font-style: normal;
+  font-weight: 100 900;
+  font-display: swap;
+}
+body { margin: 0; background: #ffffff; }
+main { padding: 16px; }
+#chart-host { min-width: 0; }
+html[data-orgchart-mode="readOnly"] body { background: #F5F8FB; }