feat(usable): integrate current dbtool implementation snapshot

Co-Authored-By: Paperclip <noreply@paperclip.ing>

examples/fixtures/postgres/init.sql

@@ -1,5 +1,31 @@
+DO $$
+BEGIN
+  IF NOT EXISTS (SELECT 1 FROM pg_roles WHERE rolname = 'dbtool') THEN
+    CREATE ROLE dbtool
+      LOGIN
+      PASSWORD 'dbtool'
+      NOSUPERUSER
+      NOCREATEDB
+      NOCREATEROLE
+      INHERIT;
+  ELSE
+    ALTER ROLE dbtool
+      WITH LOGIN
+      PASSWORD 'dbtool'
+      NOSUPERUSER
+      NOCREATEDB
+      NOCREATEROLE
+      INHERIT;
+  END IF;
+END
+$$;
+
+GRANT CONNECT ON DATABASE dbtool_demo TO dbtool;
+
 DROP SCHEMA IF EXISTS qa_demo CASCADE;
-CREATE SCHEMA qa_demo;
+CREATE SCHEMA qa_demo AUTHORIZATION postgres;
+GRANT USAGE ON SCHEMA qa_demo TO dbtool;
+ALTER ROLE dbtool IN DATABASE dbtool_demo SET search_path TO qa_demo, public;
 SET search_path TO qa_demo;
 
 CREATE TABLE accounts (
@@ -30,3 +56,6 @@ INSERT INTO tickets (id, account_id, title, status, notes, amount_cents, created
   (102, 1, 'csv export mismatch', 'closed', 'fixed after re-run', 1500, '2026-03-21T11:15:00Z'),
   (103, 2, '权限验证', 'open', 'needs DBA review', 300, '2026-03-22T15:30:00Z'),
   (104, 3, 'emoji smoke 😀', 'open', NULL, 42, '2026-03-23T07:05:00Z');
+
+GRANT SELECT ON ALL TABLES IN SCHEMA qa_demo TO dbtool;
+ALTER DEFAULT PRIVILEGES IN SCHEMA qa_demo GRANT SELECT ON TABLES TO dbtool;