[feat] add initial database schema with tables, triggers, and views

database/main/culture_citation.sql

@@ -0,0 +1,14 @@
+create table culture_citation
+(
+    culture_id  INTEGER not null
+        references culture
+            on delete cascade,
+    citation_id INTEGER not null
+        references citation
+            on delete cascade,
+    primary key (culture_id, citation_id)
+);
+
+create index idx_culture_citation_cit
+    on culture_citation (citation_id);
+