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.
Consolidate SecureStoreLockedFormView and SecureStoreUnlockedFormView into
a single SecureStoreInfoFormView that displays store status and metadata.
Simplifies MainWindowViewModel by removing redundant state management.
Also adds design docs for RegexTransformer feature.
Add SecureStore integration to ConfigManager for secure handling of connection
strings and sensitive configuration values. Includes store/secret management
UI, encrypted .store file support, and comprehensive test coverage.