Add Token Budget extension to community catalog (#2712)

* Add Token Budget extension to community catalog

Add token-budget extension submitted by @tinesoft to:
- extensions/catalog.community.json (alphabetical order)
- docs/community/extensions.md community extensions table

Closes #2687

* Fix alphabetical order: Token Budget before Token Consumption Analyzer

* Fix tools entry: use 'python3' instead of 'python3 + tiktoken'