Harden compliance portal auth and TLS

Align console references and OAuth branding with the
compliance-page model, and fix certificate cache eviction,
portal OAuth handlers, and magic-link edge cases left after
the trust-center rename.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/cmd/trust-center/update/update.go

@@ -182,7 +182,11 @@ func NewCmdUpdate(f *cmdutil.Factory) *cobra.Command {
 			}
 
 			if cmd.Flags().Changed("email") {
-				input["email"] = flagEmail
+				if flagEmail == "" {
+					input["email"] = nil
+				} else {
+					input["email"] = flagEmail
+				}
 			}
 
 			if cmd.Flags().Changed("headquarter-address") {