Add JSON format support to session destroy for native API clients

This is so that native API clients can get the session record deleted
server-side. They still need to take care of clearing any cookies
they've set in web views.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/controllers/sessions_controller.rb

@@ -20,7 +20,11 @@ class SessionsController < ApplicationController
 
   def destroy
     terminate_session
-    redirect_to_logout_url
+
+    respond_to do |format|
+      format.html { redirect_to_logout_url }
+      format.json { head :no_content }
+    end
   end
 
   private