Repo: add AI assistant-specific commands for common git workflows

[krokoko]

Describe the feature

Add AI assistant-specific slash commands to the repository for common git and GitHub workflows such as gh-commit, gh-new-pr, gh-review, etc. These commands would encode our repository conventions (worktree workflow, commit message format, PR template, etc.) so that any AI assistant working in this repo follows them consistently.

Use Case

When AI assistants (Claude Code, Cursor, Kiro, etc.) work in this repository, they need to follow specific conventions documented in CLAUDE.md -- for example, running mise run build before committing, and following our PR template. Currently each assistant must interpret CLAUDE.md each time. Purpose-built commands would:

• Standardize commit messages across all contributors (human and AI)
• Ensure PRs follow the repository template and include required sections
• Run the full build validation before committing
• Reduce errors from assistants that miss or misinterpret conventions

Proposed Solution

For instance, add commands for the following workflows:

gh-commit

• Stage specified files (or prompt for which files)
• Run mise run build to validate before committing
• Generate a conventional commit message based on the diff
• Create the commit with appropriate Co-Authored-By trailer

gh-new-pr

• Ensure work is on a worktree branch (not main)
• Push the branch to the remote
• Create a PR using gh pr create with the repository's PR template
• Auto-populate the summary from commit messages

gh-review

• Fetch PR details using gh
• Run the existing review agents/skills on the PR diff
• Post review comments

...

Other Information

• These commands should be implemented as plugin commands (.md files with YAML frontmatter)
• They should use mise tasks where appropriate (e.g., mise run build for validation)

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change