cli: add positional args for users search and messages send

[salmonumbrella]

Summary

• Add search and find as aliases for users list, so inline users search isaac works
• Make users list filter a positional arg instead of --filter, so inline users list isaac works
• Add trailing positional text support to messages send, so inline messages send --chat-id 304 hello world works alongside the existing --text flag

All changes are backward-compatible — the --text flag continues to work as before.

Before / After

# Before (errors)
inline users search isaac        # "unrecognized subcommand 'search'"
inline messages send 304 "hi"    # "unexpected argument '304'"

# After (works)
inline users search isaac        # finds Isaac
inline users list isaac           # also works (positional filter)
inline messages send --chat-id 304 hello world   # sends "hello world"
inline messages send --chat-id 304 --text "hi"   # still works (flag syntax)

[morajabi]

Not merging this PR directly; we incorporated the desired CLI ergonomics ideas (users search/find desire paths) in follow-up commits, without adding positional send.