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

database/main/trg_requirement_check_exclgrp_insert.sql

@@ -0,0 +1,10 @@
+CREATE TRIGGER trg_requirement_check_exclgrp_insert
+BEFORE INSERT ON requirement
+WHEN NEW.req_type='EXCLUSIVE_GROUP'
+BEGIN
+  SELECT CASE
+    WHEN NEW.req_id IS NULL OR NOT EXISTS (SELECT 1 FROM exclusive_group WHERE id=NEW.req_id)
+    THEN RAISE(ABORT,'requirement.req_id must reference exclusive_group.id for EXCLUSIVE_GROUP')
+  END;
+END;
+