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

sql/migration.sql

@@ -637,3 +637,23 @@ ALTER TABLE projects ADD COLUMN IF NOT EXISTS progress DOUBLE PRECISION DEFAULT
 ALTER TABLE projects ADD COLUMN IF NOT EXISTS updated_at TIMESTAMPTZ DEFAULT now();
 
 COMMIT;
+
+-- ---------- PANEL ACCESS (جایگزین مدل نقش) ----------
+-- تخصیص پنل + سطح دسترسی به ازای هر کاربر و عضویت M:N پروژه‌ای
+CREATE TABLE IF NOT EXISTS user_panels (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    panel      TEXT NOT NULL CHECK (panel IN ('procurement', 'inventory', 'pm')),
+    level      TEXT NOT NULL CHECK (level IN ('full', 'limited')),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (user_id, panel)
+);
+CREATE TABLE IF NOT EXISTS user_project_members (
+    id         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    user_id    UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    project_id UUID NOT NULL REFERENCES projects(id) ON DELETE CASCADE,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (user_id, project_id)
+);
+
+COMMIT;