pm close: add common short aliases -m (message), -r (reason), -d (duplicate-of) #226

Problem

pm close supports --message, --reason, and --duplicate-of flags, but has no short aliases for them. This is inconsistent with -h, --help which does have a short form. Users (especially agents typing many commands) naturally try -m for message, -r for reason, and -d for duplicate-of, which all fail.

Current behavior

$ pm close pm-a1b2 -m "Closing after verification"
error: unknown option `-m`

$ pm close pm-a1b2 -r "All criteria met"
error: unknown option `-r`

$ pm close pm-a1b2 -d pm-c3d4
error: unknown option `-d`

But -h works:

$ pm close -h
Usage: pm close [options] <id> [text]

The long forms work:

$ pm close pm-a1b2 --message "Closing after verification"   # OK
$ pm close pm-a1b2 --reason "All criteria met"              # OK
$ pm close pm-a1b2 --duplicate-of pm-c3d4                   # OK (with caveats per #204)

Real-world impact from the 3d-bots audit

During the 2026-06-12 audit, 10+ items were closed with commands like:

pm close pm-7007 --duplicate-of pm-x7yo --message "Close duplicate" --author codex

Each command is 80+ characters. With short aliases this becomes:

pm close pm-7007 -d pm-x7yo -m "Close duplicate" --author codex

For agents running batch close operations on 50+ items, this saves ~2000 characters of output and reduces token usage significantly.

Suggested implementation

Add these short aliases (mirroring common conventions):

• -m for --message
• -r for --reason (alias for positional )
• -d for --duplicate-of

These are safe single-letter flags that will not conflict with future options:

• -f is already --force
• -h is already --help
• No other -m, -r, or -d flags exist on pm close

No behavioral changes -- just shorthand for existing long-form flags.