Regzbot Library

Reorganize the code, and/or documentation, to allow more users to interact with it directly, in addition to the mailing list `#regzbot` tokens, and the web-ui.

Note that tracking regressions progress by looking out for replies, crosslinks, and fixes over multiple domains (mailing lists on lore, bugzilla, github, gitlab instances and fixes that reach the tree where it needs to be, e.g. next, mainline and/or stable) work great today.

Duplication handling also works great (regzbot does not care which of the regressions is the main one, it just merges them into one)

It also forgets regressions after some time of inactivity

The command interface, does the trick, but has some warts

Start with docs/reference.md and the existing command interface described in the issue. Determine the intended direct-interaction surface and how it should coexist with mailing-list tokens and the web UI; the work is done when that scope and its user-facing behavior are documented and implemented.

Written by the indexing model from the issue text.