feat(i18n): 管理端与玩家端三语支持（中/英/马来语）

- 管理后台 adminT 文案库、结算与代理端页面、表单校验
- 玩家端 vue-i18n 补全首页/公告/串关与 ms 文案
- Element Plus ms 语言包与共享 locale 工具

apps/admin/src/views/agent-form.ts

@@ -1,3 +1,5 @@
+import { FormValidationError } from '../i18n/form-validation';
+
 export interface AgentCreateForm {
   username: string;
   password: string;
@@ -81,10 +83,10 @@ export function editFormFromAgentDetail(d: AgentDetail): AgentEditForm {
 }
 
 export function buildCreateAgentPayload(form: AgentCreateForm) {
-  if (!form.username.trim()) throw new Error('请填写用户名');
-  if (form.password.length < 8) throw new Error('密码至少 8 位');
-  if (form.password !== form.confirmPassword) throw new Error('两次密码不一致');
-  if (form.creditLimit < 0) throw new Error('授信额度不能为负');
+  if (!form.username.trim()) throw new FormValidationError('err.username_required');
+  if (form.password.length < 8) throw new FormValidationError('err.password_min');
+  if (form.password !== form.confirmPassword) throw new FormValidationError('err.password_mismatch');
+  if (form.creditLimit < 0) throw new FormValidationError('err.credit_negative');
   return {
     username: form.username.trim(),
     password: form.password,