inconsistent semantics for how to "access" a user

In a user link, (e.g. https://matrix.to/#/@uhoreg:matrix.org), matrix.to lists a link for Riot such as https://riot.im/app/#/user/@uhoreg:matrix.org, which will show the user's profile, whereas for the other clients it says to type "/invite @uhoreg:matrix.org", which will invite the user to the room.

Since different clients may support different actions for users, and clients may support multiple possible actions, so it may be good to list multiple ways of interacting with the user and a description of what it does, such as:

Name | ... | Access @uhoreg:matrix.org | .
----|----|----|----
Riot | ... | View profile | https://riot.im/app/#/user/@uhoreg:matrix.org
. | ... | Start chat | (something once vector-im/riot-web#4034 is fixed)
. | ... | Invite to a room | Type `/invite @uhoreg:matrix.org`
WeeChat | ... | Invite to a room | Type `/invite @uhoreg:matrix.org`
etc... |

It might also be useful to be able to add a parameter to the matrix.to link to specify a certain action. For example, something like https://matrix.to/#/@uhoreg:matrix.org?action=chat would mean that someone clicking on the link should start a chat with @uhoreg:matrix.org. (cf. [XEP-0147](https://xmpp.org/extensions/xep-0147.html))

Start by reviewing the matrix.to redirect behavior and the client examples in this issue. The proposed work spans describing multiple user actions, client-specific instructions, and possibly an action parameter; done would require an agreed design and defined behavior for those cases. The issue has no file or test references, so repository structure and existing URL handling must be investigated first.

Written by the indexing model from the issue text.