chore(pm): vendor the Aramesh/PM platform under pm/ (squash of Aramesh/PM @ 91f3271)

The PM panel (PmPanelPage -> iframe /pm/) needs the project-management
platform served at /pm/ on the ERP domain. Source: org repo Aramesh/PM,
branch feature/project-management-platform. Update via:
git subtree pull --prefix=pm aramesh-pm feature/project-management-platform --squash

pm/frontend/src/vite-env.d.ts

@@ -0,0 +1,6 @@
+/// <reference types="vite/client" />
+
+interface ImportMetaEnv {
+  // آدرس سامانه ERP (تدارکات/انبار) برای منوی «پنل‌ها» — خالی = پیش‌فرض لوکال
+  readonly VITE_ERP_URL?: string;
+}