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/Dockerfile

@@ -0,0 +1,17 @@
+# ---- مرحله ساخت ----
+FROM node:22-alpine AS build
+WORKDIR /app
+
+COPY package.json package-lock.json ./
+RUN npm ci
+
+COPY . .
+RUN npm run build
+
+# ---- مرحله اجرا ----
+FROM nginx:alpine
+COPY nginx.conf /etc/nginx/conf.d/default.conf
+COPY --from=build /app/dist /usr/share/nginx/html
+
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]