feat: add topic hierarchy APIs

src/types/database.ts

@@ -1,7 +1,8 @@
-import type { FactRecord, FactTopicRecord, TopicRecord } from './domain';
+import type { FactRecord, FactTopicRecord, TopicRecord, TopicRelationRecord } from './domain';
 
 export interface IdentityDatabaseSchema {
   topics: TopicRecord;
   facts: FactRecord;
   fact_topics: FactTopicRecord;
+  topic_relations: TopicRelationRecord;
 }