chore: point the floret-kit submodule at Codeberg

First step of moving the canonical forge to Codeberg. floret-kit now
lives at codeberg.org/jlmakiola/floret-kit with identical history — all
six branches and three tags mirrored, every SHA verified equal.

This is the piece that actually unblocks outside contributors: a clone
of Calendula previously could not resolve its submodule without reaching
the personal Gitea instance, so the whole build depended on that host
staying up even though the issues live on Codeberg.

The Gitea copy is deliberately kept, not deleted: every existing tag
records the old submodule URL in its .gitmodules, so any rebuild of a
past release — including an F-Droid reproducible rebuild — still
resolves against it. It becomes the target of a push mirror rather than
a source of truth.

Existing checkouts need 'git submodule sync --recursive' after pulling
this; the submodule commit itself is unchanged.

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "floret-kit"]
 	path = floret-kit
-	url = https://gitea.jeanlucmakiola.de/makiolaj/floret-kit.git
+	url = https://codeberg.org/jlmakiola/floret-kit.git