feat: add wutta top-level command with make-uuid subcommand

i think it only makes sense to have an "opinion" for command line
interface in this project, and we probably need more `wutta`
subcommands too but we'll see.

main motivation for this currently is to allow poser apps to define
their own CLI, in particular e.g. `poser install`

docs/narr/cli/index.rst

@@ -2,9 +2,24 @@
 Command Line Interface
 ======================
 
+Most apps will need some sort of command line usage, via cron or
+otherwise.  There are two main aspects to it:
+
+There is a proper CLI framework based on `Typer`_, with top-level
+:term:`commands<command>` and :term:`subcommands<subcommand>`.  The
+``wutta`` command is built-in and includes some subcommands, but each
+app can define more of either as needed.  Such (sub)commands are
+installed as part of a :term:`package`.
+
+.. _Typer: https://typer.tiangolo.com
+
+But sometimes you just need an :term:`ad hoc script` which is a single
+file and can be placed anywhere, usually *not* installed as part of a
+package.
+
 .. toctree::
    :maxdepth: 2
 
-   overview
-   commands
+   builtin
+   custom
    scripts