canonicalProviderName function
The canonical provider identity of name: alias spellings fold onto
their canonical id (case-insensitive); unknown names map to
themselves (lowercased). One auth domain — one identity, across the
registry, the picker rows, and the current marker.
Implementation
String canonicalProviderName(String name) {
final lower = name.trim().toLowerCase();
return providerNameAliases[lower] ?? lower;
}