Serve the OAuth client metadata document

A public client identifies itself to the provider with a hosted
Client ID Metadata Document. Serve it unauthenticated and outside the
auth group, since the provider fetches it server-to-server, exposing the
deployment-derived client_id and redirect_uri alongside the Probo brand
name, homepage and logo.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/server/api/console/v1/resolver.go

@@ -128,6 +128,12 @@ func NewMux(
 		)
 	})
 
+	// Public, unauthenticated: the OAuth Client ID Metadata Document (CIMD)
+	// is fetched server-to-server by public-client providers (PostHog)
+	// during authorization, with no Probo credentials. Mounted outside the
+	// auth group above.
+	r.Get("/connectors/oauth-client-metadata", handleConnectorOAuthClientMetadata(baseURL))
+
 	return r
 }