This adds a new `gmail thread modify` subcommand that uses the Gmail API's
Threads.Modify endpoint to apply label changes to all messages in a thread
at once.
Usage:
gog gmail thread modify <threadId> --add "Label1,Label2" --remove "Label3"
Features:
- Resolves label names to IDs automatically
- Supports both adding and removing labels in a single operation
- JSON output mode for programmatic use
BREAKING CHANGE: The `gmail thread` command is now a parent command with
subcommands. Use `gmail thread get <id>` instead of `gmail thread <id>`.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
