fix: stabilize tests and refine RBAC model for privileged roles

- Updated devfront to recognize 'rp_admin' and 'tenant_admin' as privileged developer roles.
- Added specific forbidden messages for privileged roles in devfront.
- Improved adminfront Worksmobile test reliability across browsers.
- Updated Makefile to skip userfront tests in environments without Flutter SDK.
- Applied lint and format fixes across adminfront and devfront.

adminfront/src/components/layout/AppLayout.tsx

@@ -190,13 +190,13 @@ function AppLayout() {
 
   const navItems = React.useMemo<ShellSidebarNavItem[]>(() => {
     const items = [...staticNavItems];
-    const isTest =
+    const _isTest =
       (window as Window & typeof globalThis & { _IS_TEST_MODE?: boolean })
         ._IS_TEST_MODE === true;
     const effectiveRole = profile?.role;
 
     const isSuperAdmin = isSuperAdminRole(effectiveRole);
-    const manageableCount = profile?.manageableTenants?.length ?? 0;
+    const _manageableCount = profile?.manageableTenants?.length ?? 0;
     const showWorksmobile = canAccessWorksmobile({
       ...profile,
       role: effectiveRole ?? profile?.role,