[Feature Request]: Add /review slash command for code review workflow

What feature would you like to see?

A /review slash command that reviews the current codebase, recent changes, or a specific file/diff — similar to the /review command in Claude Code and Codex.

Why?

Code review is a high-frequency developer workflow. Having a built-in /review command would allow users to quickly get AI feedback on:

• Uncommitted changes in the working directory
• A specific file or set of files
• The most recent commit or PR diff

This reduces friction compared to manually prompting the agent with "please review these changes."

Proposed behavior

/review              # Review uncommitted changes (git diff)
/review <file>       # Review a specific file
/review --commit     # Review the most recent commit
/review --pr         # Review the current PR diff (if applicable)

The agent should analyze the diff/code and provide structured feedback covering:

• Correctness / potential bugs
• Code style and readability
• Performance concerns
• Security issues
• Suggestions for improvement

Prior art

• Claude Code: /review analyzes working tree changes and provides inline feedback.
• Codex: /review supports reviewing diffs and specific files.

The issue does not name files or existing command entry points. Start by locating slash-command dispatch and the code that reads git diffs or pull-request context; compare those paths with the proposed /review modes. Done means the command handles the listed targets and produces structured feedback for correctness, style, performance, security, and improvements.