Fix authentication configuration and Keycloak setup

[ldangelo]

This PR addresses the authentication failed error with null error_uri in FxExpert.Blazor login.

Changes Made:

• Fixed Keycloak client configuration to use HTTP URLs matching the app
• Updated redirect URIs to exact callback paths: http://localhost:8500/signin-oidc
• Fixed post logout redirect URI to: http://localhost:8500/signout-callback-oidc
• Disabled Pushed Authorization Requests (PAR) in Keycloak client config
• Added logging for authentication redirects to aid in debugging

Technical Details:

• Updated realm-export.json with corrected protocol (HTTP vs HTTPS)
• Set require.pushed.authorization.requests to false in Keycloak client
• Ensured callback URL consistency between app and Keycloak configuration

Testing:

• Keycloak container restarted to apply configuration changes
• App builds and runs successfully on localhost:8500
• Configuration mismatches between app and Keycloak have been resolved

This resolves the FOR-16 authentication issues and should allow successful login flow.