Gentoo package does not build/install Keybase at /opt/keybase/Keybase

Hello, I am using the official ebuild of keybase and kbfs and while I have the command line working fine (although I did experience an issue already posted #16050 where it does not generate the `/keybase` mountpoint correctly and I had to create the mount point in `~/.config/keybase` to get it to work at all, and eventually download and run a copy of `post_install.sh` to fix it to where it shows up in `/keybase` like it should) I cannot get the desktop to work. When I check the desktop logs, I see

```
/usr/bin/run_keybase: line 121: /opt/keybase/Keybase: No such file or directory
```

For every attempt to run it. Indeed, there is no `Keybase` at `/opt/keybase/` nor does a freshly updated locate command find the `Keybase` binary or script.

I am using i3 as my window manager, though as there are no USE flags for this package, it does not seem like it should matter as to whether or not it builds and installs `Keybase` to the correct location

Start by inspecting the official Gentoo ebuild and the /usr/bin/run_keybase entry point, then compare its expected /opt/keybase/Keybase path with the installed package contents. Done means the Keybase desktop binary is installed at the expected location and desktop launch attempts no longer report that it is missing.

Written by the indexing model from the issue text.