feat(org): panel-based access system replacing roles (procurement/inventory)

- new tables user_panels (panel: procurement/inventory/pm + level full/limited)
  and user_project_members (M:N membership, separate from pm responsibility)
- UserContext carries panels + member_project_ids; /users/me and the users
  list include them
- admin endpoints: PUT /users/{id}/panels, PUT /users/{id}/panel-projects
- inventory scope: panel inventory 'full' -> manager scope (all projects, NO
  stock change); 'limited' -> supervisor scope (own memberships, stock change
  allowed); legacy roles kept as migration fallback; admin untouched
- procurement writes: _procurement_writer is now panel-aware (admin, legacy
  procurement_manager, or procurement 'full') across all 18 write routers;
  quote CREATE additionally allows 'limited' users restricted to their member
  projects (validated server-side)
- frontend: panel-aware HomeRoute (inventory -> warehouse panel, procurement
  limited -> minimal RequesterHome), wizard project options restricted for
  limited users, change-inventory button/route gated to inventory 'limited',
  organization panel gains the panels & access-levels management section

frontend/src/pages/Wizard/Step4Projects.tsx

@@ -14,6 +14,8 @@ export interface Step4Props {
   onAssign: (tempId: string, proj: string) => void;
   onUnassign: (tempId: string, proj: string) => void;
   onAddProject: (name: string) => void;
+  /** سطح limited تدارکات: افزودن پروژه جدید ممنوع */
+  canAddProject?: boolean;
 }
 
 const ALL_KEY = "__all__";
@@ -111,7 +113,7 @@ function DroppableProject({
 }
 
 // مرحله ۴ — تخصیص پروژه‌ها با درگ‌اندروپ (یا کلیک-قلم بعد کلیک-پروژه)
-export function Step4Projects({ items, projects, assignment, onAssign, onUnassign, onAddProject }: Step4Props) {
+export function Step4Projects({ items, projects, assignment, onAssign, onUnassign, onAddProject, canAddProject = true }: Step4Props) {
   const [picked, setPicked] = useState<string | null>(null);
   const [newProj, setNewProj] = useState("");
 
@@ -213,8 +215,8 @@ export function Step4Projects({ items, projects, assignment, onAssign, onUnassig
             {!projects.length && (
               <div className="dd-empty">هنوز پروژه‌ای تعریف نشده است — از پایین یک پروژه اضافه کنید.</div>
             )}
-            {/* افزودن پروژه به‌صورت درجا — زیر لیست پروژه‌ها */}
-            <div className="mt-3 rounded-md border border-dashed border-line p-2">
+            {/* افزودن پروژه به‌صورت درجا — زیر لیست پروژه‌ها (سطح limited: ممنوع) */}
+            <div className="mt-3 rounded-md border border-dashed border-line p-2" hidden={!canAddProject}>
               <div className="mb-1.5 text-[11.5px] font-semibold text-muted">افزودن پروژه‌ی جدید:</div>
               <div className="flex items-center gap-2">
                 <input