feat(opencode): add committed review type to review command

[rluisr]

What does this PR do?

Adds a new committed review type to the /review command. This allows users to review the most recent commit by running git diff HEAD^ HEAD.

Previously, the review command supported:

• branch - review current branch changes
• staged - review staged changes
• unstaged - review unstaged changes
• pr - review a PR from GitHub

This PR adds:

• committed - review the last committed changes

This is useful when you've just committed changes and want to quickly review what was included in that commit.

How did you verify your code works?

Tested the review command with "committed" input to confirm it correctly identifies the review type and would run git diff HEAD^ HEAD.

[github-actions]

Thanks for your contribution!

This PR doesn't have a linked issue. All PRs must reference an existing issue.

Please:

1. Open an issue describing the bug/feature (if one doesn't exist)
2. Add Fixes #<number> or Closes #<number> to this PR description

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

No duplicate PRs found

[github-actions]

Closing this pull request because it has had no updates for more than 60 days. If you plan to continue working on it, feel free to reopen or open a new PR.