Clean up repo: remove amplify.yml, update gitignore

Delete deprecated Amplify config leftover from Gitea migration.
Update next-env.d.ts for Next.js 15.5 route types.
Add .mcp.json and *.png to gitignore.

next-env.d.ts

@@ -1,5 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
+/// <reference path="./.next/types/routes.d.ts" />
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.