`_parse_target_ref` has explicit-reference branches for Telegram, Feishu,
and numeric IDs, but none for Matrix. As a result, callers of
`send_message(target="matrix:!roomid:server")` or
`send_message(target="matrix:@user:server")` fall through to
`(None, None, False)` and the tool errors out with a resolution failure —
even though a raw Matrix room ID or MXID is the most unambiguous possible
target.
Three-line fix: recognize `!…` as a room ID and `@…` as a user MXID when
platform is `matrix`, and return them as explicit targets. Alias-based
targets (`#…`) continue to go through the normal resolve path.
03446e06bb