Draw a wallpaper on a machine that has no theme yet

Seeding the config gets the bar and the keybindings up, and then leaves
you looking at a black screen, because the autostart line that sets the
wallpaper named ~/.local/share/wallpapers/hyprcosmic/current directly.
That is a symlink import-theme --assets maintains, so it does not exist
until a theme has been imported -- which on a machine that has just
installed the package it has not.

The same line waited for the daemon with an unbounded loop:

    until awww query >/dev/null 2>&1; do sleep 0.2; done

awww is a Recommends and lives in a COPR, so on a machine that never
enabled that repository nothing ever answered and the loop spun at 5 Hz
for the length of the session.

Both now live in hyprcosmic-wallpaper, which falls back to the
distribution's own images when there is no link yet, gives up on the
daemon after ten seconds, and exits 0 on every path so autostart is never
left supervising a process that cannot finish. Fedora recommends
cosmic-wallpapers so the fallback has something to find; nothing in the
dependency chain pulled it in before.

Verified against all five paths: no awww at all, a daemon that never
answers, a fresh machine with no link, a link pointing at a real file,
and a link left dangling by a deleted theme.

README.md

@@ -195,6 +195,15 @@ Runtime dependencies of the shell itself are not COSMIC's and are not built
 here: `waybar`, `rofi` (wayland build), `awww` (formerly `swww`), and a Nerd
 Font for the glyphs the bar and the launcher draw with.
 
+The wallpaper is `awww`'s job, and the image it draws is
+`~/.local/share/wallpapers/hyprcosmic/current` — a symlink `import-theme
+--assets` maintains. Before you have imported a theme there is no such link, so
+`hyprcosmic-wallpaper` falls back to whatever the distribution ships,
+`/usr/share/backgrounds/cosmic` first; the Fedora package recommends
+`cosmic-wallpapers` so there is something there. With no `awww` installed it
+says so on the session log and leaves the background alone, rather than waiting
+for a daemon that is never coming.
+
 The font is the one thing the packaging cannot do for you on Fedora, which has
 no package that provides a Nerd Font at all: `texlive-inconsolata-nerd-font`
 installs under `texmf-dist` and kitty's `SymbolsNerdFont` under