/ppr

Prepare feature branch for PR with linear history workflow

# Prepare PR (ppr)

> Quick command: `/gdf:ppr [base-branch]` or `/ppr [base-branch]`
>
> Prepares feature branch for pull request by ensuring linear history,
> running tests, and creating PR with generated summary.

## Quick Reference

- **Usage**: `/ppr` or `/ppr main`
- **Arguments**:
  - `base-branch` (optional): Target branch for PR (defaults to main/master)
- **Prerequisites**: Feature branch with commits
- **Output**: Created pull request with summary and test plan

## Error Handling

- **Not on feature branch**: Shows error and current branch name
- **No commits to PR**: Shows error...