Replace Referer-based redirects in Admin Index back() and switchUser()
with named routes (admin.index and dashboard) for consistent navigation
behavior independent of the request header.
Add tests verifying back() returns to admin.index, switchUser routes to
the dashboard, and the Referer header is no longer consulted.
Move the admin panel route into the existing auth middleware group and
replace client-side redirects with server-side abort calls in the
Livewire component. Extract shared authorization logic into reusable
private methods.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>