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/.gitignore

@@ -0,0 +1,23 @@
+# secrets & local state — never commit
+.env
+.env.local
+
+# python
+__pycache__/
+*.pyc
+.venv/
+venv/
+
+# node
+node_modules/
+dist/
+*.local
+
+# editor / OS
+.vscode/
+.idea/
+Thumbs.db
+.DS_Store
+
+# uploaded defect photos (runtime volume)
+files/