Add Forgejo Actions workflows and fix [breadway] repo URL

- .forgejo/workflows/mirror.yml: mirrors every push/tag to GitHub
- .forgejo/workflows/package.yml: builds PKGBUILD on tag and publishes
  bos-settings to the Forgejo Arch package registry (distrib=breadway)
- iso/pacman.conf: replace placeholder repo.breadway.dev with the actual
  Forgejo package registry URL

Requires two Forgejo secrets:
  GITHUB_MIRROR_TOKEN — GitHub PAT with repo push scope
  FORGEJO_TOKEN       — Forgejo token with package:write scope

iso/pacman.conf

@@ -30,9 +30,10 @@ Include = /etc/pacman.d/mirrorlist
 # bread ecosystem packages (bread, breadbar, breadbox, breadcrumbs, breadpad,
 # bos-settings).
 #
-# TODO: Replace this URL with the actual hosted repo before building.
-# See: https://github.com/Breadway/repo for setup instructions.
+# Packages are published here by the Forgejo Actions package.yml workflow
+# in each repo. See git.breadway.dev/api/packages/breadway/arch for the
+# package registry.
 # -----------------------------------------------------------------------
 [breadway]
 SigLevel = Optional TrustAll
-Server = https://repo.breadway.dev/$arch
+Server = https://git.breadway.dev/api/packages/breadway/arch/breadway/$arch