Install the desktop before anything allowed to fail, and let Terra be installed twice

Two bugs, one story: ./install on a machine that had been half set up before
produced no Hyprland at all, and said so in one line among twenty minutes of
scrollback.

Terra bootstraps itself with --repofrompath, which defines a throwaway repo id
just long enough to install terra-release. Run it again on a machine that
already has terra-release and dnf5 refuses the whole transaction -- the
throwaway id collides with the real one. That step sits above everything, so
set -e ended the stage before a single package was considered. It is skipped
now when terra-release is already installed.

The rest is the reason one failed repo cost the desktop. Hyprland was installed
near the bottom of the stage, below a codec swap, two group updates and a
GStreamer glob, any one of which can fail for reasons outside this repository.
It now installs directly after the packages it needs and before anything
optional, and everything fragile below it runs through a soft helper that logs
and continues rather than ending the run. What was stepped over is listed at
the end, because tolerating a failure only beats aborting on it if somebody is
told.

A missing Hyprland is still fatal, and now says so in words.

Also removes the leftover disabled solopasha/hyprland COPR, which would mix
with lionheartp's the moment anyone enabled it while debugging.

Fixes the usage widget reading 1500%: the endpoint reports percentages, not
0..1 fractions. Clamped as well, and the widget answers a click now -- it set
interactive:false, which disables the mouse area its own handler needed.

README.md

@@ -136,7 +136,7 @@ docs/           Settings reference, and the design specs behind the work
 
 ## Tests
 
-152 of them, under `tests/`. Run the lot, or a subset by pattern:
+153 of them, under `tests/`. Run the lot, or a subset by pattern:
 
 ```sh
 panama test           # everything