Adds --all/-a flag as a semantic complement to --unread. While the
default behavior already shows all messages, --all makes the intent
explicit when viewing the complete inbox.
The flags are mutually exclusive - using both --all and --unread
returns an error.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Adds mark-read and mark-unread commands that allow marking messages
as read without archiving them. Uses a "read" label to track status.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>