Add standalone repo scaffolding (README, packaging, CI)

Adds the release/CI machinery bos-settings already has in its own repo:
Forgejo package.yml (tag -> build -> publish to [breadway]) and
mirror.yml (Forgejo -> GitHub). PKGBUILD updated for the flattened
layout and dropped -p breadhelp now that this isn't a workspace member.

.forgejo/workflows/mirror.yml

@@ -0,0 +1,21 @@
+name: Mirror to GitHub
+
+on:
+  push:
+    branches: ['**']
+    tags: ['**']
+
+jobs:
+  mirror:
+    runs-on: [self-hosted, hestia]
+    steps:
+      - name: Mirror to GitHub
+        run: |
+          set -euo pipefail
+          git clone --mirror "https://git.breadway.dev/${GITHUB_REPOSITORY}.git" repo.git
+          cd repo.git
+          # Mirror only branches and tags (not refs/pull/*, which GitHub rejects);
+          # --prune deletes GitHub refs that no longer exist on Forgejo.
+          git push --prune \
+            "https://x-access-token:${{ secrets.MIRROR_TOKEN }}@github.com/Breadway/breadhelp.git" \
+            '+refs/heads/*:refs/heads/*' '+refs/tags/*:refs/tags/*'