feat: add patches debug commands for inspecting and restoring custom code

[AshGodfrey]

Summary

• Centralizes git repository opening with OpenGitRepository helper in internal/patches/git_repository.go
• Adds view-diff file command to show unified diff between pristine and current version of a single file
• Adds view-diff files command to list all files with custom code applied
• Adds restore-pristine file command to restore a single file to its pristine generated version
• Adds restore-pristine all command to restore all files with custom code to pristine
• Extracts shared config/lockfile loading into common.go to deduplicate across commands
• Uses byte comparison instead of diff computation for restore-pristine all performance

Commands

speakeasy patches
├── view-pristine -f <file>         # Show pristine (generated) version of a file
├── view-diff
│   ├── file -f <file>              # Show diff between pristine and current
│   └── files                       # List all files with custom code
└── restore-pristine
    ├── all                          # Restore all files to pristine
    └── file -f <file>              # Restore one file to pristine

Test plan

• Tested all commands against tag-test SDK (TypeScript) and client-python-private (Python)
• Verified view-diff files only reports files with actual content changes vs pristine (not deletions/moves)
• Verified restore-pristine all correctly restores multiple files and reports count
• Verified idempotency — running restore-pristine all twice shows no files on second run
• go build succeeds

🤖 Generated with Claude Code