feat: add knowledge graph component and persistent handbook sync state collection

src/lib/db.js

@@ -308,3 +308,20 @@ export async function bulkSetCurriculum(year, weeks) {
   );
 }
 
+// ── Handbook Sync State ───────────────────────────────────────────────────────
+
+export async function getHandbookSyncStates() {
+  try {
+    return await pb.collection('handbook_sync_state').getFullList();
+  } catch { return []; }
+}
+
+export async function updateHandbookSyncState(path, sha) {
+  try {
+    const r = await pb.collection('handbook_sync_state').getFirstListItem(`path="${path}"`);
+    return await pb.collection('handbook_sync_state').update(r.id, { sha });
+  } catch {
+    return await pb.collection('handbook_sync_state').create({ path, sha });
+  }
+}
+