feat: add admin user management and disable public registration

apps/api/src/user-access.ts

@@ -0,0 +1,16 @@
+import { z } from 'zod';
+import { credentials } from './validation';
+
+export const roles = z.enum(['admin', 'user', 'readonly']);
+export const loginInput = credentials.extend({
+  password: z
+    .string()
+    .min(1)
+    .max(72)
+    .refine((s) => Buffer.byteLength(s, 'utf8') <= 72, '密码最多 72 字节'),
+});
+export const adminCreateInput = credentials.extend({ role: roles.default('user') }).strict();
+export const adminUpdateInput = z
+  .object({ role: roles.optional(), banned: z.boolean().optional() })
+  .strict()
+  .refine((v) => v.role !== undefined || v.banned !== undefined, '请选择权限或封禁状态');