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

database/main/trg_requirement_check_trait_update.sql

@@ -0,0 +1,10 @@
+CREATE TRIGGER trg_requirement_check_trait_update
+BEFORE UPDATE ON requirement
+WHEN NEW.req_type IN ('TRAIT','TRAIT_LEVEL_MIN')
+BEGIN
+  SELECT CASE
+    WHEN NEW.req_id IS NULL OR NOT EXISTS (SELECT 1 FROM trait WHERE id = NEW.req_id)
+    THEN RAISE(ABORT, 'requirement.req_id must reference trait.id for TRAIT/TRAIT_LEVEL_MIN (UPDATE)')
+  END;
+END;
+