Add SettingsService.ResolveString/Bool/Int resolving runtime config as
app_settings (UI) > environment variable > default. Env seeds bootstrap; any
value set in the UI persists to app_settings and wins. Foundation for OIDC and
TLS UI configuration. Unit-tested for the precedence order.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Alphaeus Mote