[Feature Request] Add CLI support for querying 5-hour rolling quota in non-interactive mode

Bug Description
There is no supported CLI flag/feature for the 5-hour quota in non-interactive mode.

• /cost works in interactive sessions and shows session token/$ usage (not the rolling-window quota).
• /usage only runs in interactive sessions; under claude -p slash commands like /status and /usage aren't dispatched.
• No documented claude usage subcommand, JSON flag, or ~/.claude/ file exposes remaining quota.

Scriptable quota check doesn't currently exist — the only UI is /usage interactively or claude.ai → Settings → Usage.

• Feedback ID: 10b487af-a92d-4c68-84c3-564c971b1102