When no active approval workflow exists, ApprovalService::submit() was
silently returning, leaving the request in Draft while showing a false
success message. Now throws a RuntimeException as a safety net, and the
Livewire component guards before creating any records and shows a clear
error to the user.
- Add missing LDAP env vars to .env.example (host, base DN, bind credentials)
- Use 'uid' instead of 'username' as the LDAP lookup attribute in Auth::attempt
- Override getLdapGuidColumn/getLdapDomainColumn in User model to match
migration column names (ldap_guid/ldap_domain vs default guid/domain)
