Add recursive git clean command

[bupd]

Need a command that walks git repos under the current directory and aggregates cleanup output.

Requirements:

• default mode previews recursively across repos
• delete subcommand performs the cleanup
• show reclaimable size per repo
• show total reclaimable space at the end
• protect .env* and .claude by default
• support --not-delete <pattern>
• support --ignore-dir <path>
• print the exact delete command at the end of preview