Show SAML signing certificate for IdPs

New Feature Request

Summary

Problem:
IdP admins cannot see which SAML signing certificates are currently configured for their IdP.

Value:
Managing updated certificated requires lots of interaction with the support that at the moment. Giving the IdP insight in the current config (and maybe allow them to update the config themselves) would help.

Proposed Solution

• Action:
  Add a screen that shows technische information about an IdP. This should include the SAML signing certificate, both in PEM format and the human-readable metadata (see openssl x509 -noout -text).

• Design:
  tbd

• Impact:
  no. New feature.

Developer Checklist

To be completed by the developer during implementation.

• Add required changes and feature flags config files
• Create and document database changes and migrations
• Create and document API changes and migrations
• check for backwards compatibility
• Updated CHANGELOG and other documentation where needed

Testing and QA

Describe how to verify and test this change.

Test Environment and Setup

1. Point to [URL/Branch]
2. Use account with [Role/Permissions]

Test Checklist

• Happy Path: Feature works as intended under normal conditions.
• Edge Case: [Describe specific test item]
• Validation: [Describe specific test item]
• UI/UX: Verified layout across screen sizes.

Extra Information

Add any other context, related issues, or technical notes here.

The issue names no files, tests, or entry points, so first locate the existing IdP administration screen and SAML configuration/API handling. Define the required permissions and UI design, then verify that the certificate is shown in PEM and human-readable forms and that the feature is covered by tests.