feat(ECR-013A): Admin RBAC 实现并 Closed

角色权限、RequirePermission、/me permissions 与 migration 000015；
Reviewer Approve → Closed。Next：ECR-013B Contract Definition。

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/api/migrations/000015_admin_rbac.down.sql

@@ -0,0 +1,4 @@
+UPDATE admin_accounts SET role_id = NULL WHERE role_id IS NOT NULL;
+ALTER TABLE admin_accounts DROP COLUMN IF EXISTS role_id;
+DROP TABLE IF EXISTS admin_role_permissions;
+DROP TABLE IF EXISTS admin_roles;

apps/api/migrations/000015_admin_rbac.up.sql

@@ -0,0 +1,42 @@
+-- ECR-013A Admin RBAC
+
+CREATE TABLE IF NOT EXISTS admin_roles (
+  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  name varchar(64) NOT NULL UNIQUE,
+  system boolean NOT NULL DEFAULT false,
+  created_at timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE TABLE IF NOT EXISTS admin_role_permissions (
+  role_id uuid NOT NULL REFERENCES admin_roles(id) ON DELETE CASCADE,
+  code varchar(64) NOT NULL,
+  PRIMARY KEY (role_id, code)
+);
+
+ALTER TABLE admin_accounts
+  ADD COLUMN IF NOT EXISTS role_id uuid REFERENCES admin_roles(id);
+
+INSERT INTO admin_roles(id, name, system)
+VALUES ('00000000-0000-4000-8000-000000000001', 'super_admin', true)
+ON CONFLICT (name) DO NOTHING;
+
+INSERT INTO admin_role_permissions(role_id, code)
+SELECT r.id, p.code
+FROM admin_roles r
+CROSS JOIN (VALUES
+  ('admin.users.read'),
+  ('admin.users.membership.grant'),
+  ('admin.users.ask_quota.grant'),
+  ('admin.orders.read'),
+  ('admin.audit.read'),
+  ('admin.analytics.read'),
+  ('admin.content.write'),
+  ('admin.roles.read'),
+  ('admin.roles.write')
+) AS p(code)
+WHERE r.name = 'super_admin'
+ON CONFLICT DO NOTHING;
+
+UPDATE admin_accounts
+SET role_id = (SELECT id FROM admin_roles WHERE name = 'super_admin')
+WHERE role_id IS NULL AND deleted_at IS NULL;