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

database/main/v_requirement_debug.sql

@@ -0,0 +1,13 @@
+CREATE VIEW v_requirement_debug AS
+SELECT
+  owner_kind,
+  owner_id,
+  group_no,
+  CASE negate WHEN 1 THEN 'NOT ' ELSE '' END || req_type AS req_op,
+  req_id,
+  req_level,
+  req_optokey,
+  note
+FROM requirement
+ORDER BY owner_kind, owner_id, group_no, negate DESC, req_type, req_id;
+