The Enterprise-Managed Authorization "Issuer" field accepted arbitrary
non-URL text and only failed at save time, surfacing a raw Zod issue array
in "Failed to save client settings" toasts.
- Inline field-level validation: the Issuer input shows a friendly error
("Must be an http(s) URL, like https://idp.example.com").
- canPersistClientSettingsDraft gates on issuer validity (deferring to
validateClientSettings) so an invalid value is never sent to the backend.
- Extract isAbsoluteHttpUrl in core/client/config-parse so the Zod schema
and the form share one http(s)-only URL rule.
- Harden the fallback save-error toast via formatClientConfigLoadError.
Closes#1533
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>