Tentatively deprecate Roo Code support pending Roomote path

## Context

Spec Kitty currently exposes a Roo Code host surface through the `roo` agent key and `.roo/commands/`. Roo Code support should be treated as tentatively deprecated unless there is a credible future integration path.

Robert has reached out to the Roo team to understand whether there is a future integration path with Roomote. We should avoid making a final removal decision until that path is understood.

## Proposal

- Mark Roo Code support as tentatively deprecated in the supported-agent documentation.
- Keep the current `roo` command surface working for existing users while the Roomote path is clarified.
- Avoid new Roo-specific feature work unless it is required for compatibility or migration.
- Revisit once Robert has feedback from the Roo team about Roomote.

## Questions to Resolve

- Is Roomote intended to provide a supported successor/integration path for Roo users?
- If yes, should Spec Kitty keep the `roo` key, add a new `roomote` key, or support both during a migration window?
- If no, what release should formally deprecate or remove Roo Code support?

## Tentative Acceptance Criteria

- Documentation clearly states Roo Code support is tentative/deprecated pending Roomote clarification.
- Existing projects using `--ai roo` are not broken without an explicit migration plan.
- A follow-up decision records whether Spec Kitty will maintain, migrate, or remove the Roo surface.