Proposal: Move diff, bundler, and optimizer into CLI

As part of the 2026 community goals (more details here: https://github.com/asyncapi/community/issues/3495), we conducted an audit of all repositories. The summary of the findings can be found here: https://github.com/asyncapi/community/issues/3495#issuecomment-4681625773.

As suggested by @deberg, we are proposing to move the `diff`, `bundler`, and `optimizer` repositories to the CLI repository.

Reference to the conversation:
- https://asyncapi.slack.com/archives/C34F2JV0U/p1774973085382029?thread_ts=1774874525.585229&cid=C34F2JV0U
- https://github.com/asyncapi/community/issues/3495

I am opening this issue to gather feedback and approval from the code owners of this repository regarding the proposal to move this repository to CLI.

Tagging all code owners for their feedback and approval.
@aeworxet

Start by reading the linked community issue, its audit summary, and the referenced conversation about moving the diff, bundler, and optimizer repositories. The immediate outcome is code-owner feedback and approval or rejection of the proposal; this issue does not name implementation files or tests.

Written by the indexing model from the issue text.