Eliminates placeholder substitution (${KEY}) in favor of storing complete
connection strings as single encrypted values. SecureStore now auto-creates
entries for all connection strings defined in appsettings. ConfigManager
editor reads/writes values directly to SecureStore.
Set up repository with legacy .NET Framework 4.8 source (OLD/),
new .NET 10 Blazor solution (NEW/), OpenSpec specifications,
documentation, and project configuration.