Add packaging/arch PKGBUILD and Forgejo Actions workflows

- packaging/arch/PKGBUILD: builds and publishes breadcrumbs to [breadway] repo
- .forgejo/workflows/mirror.yml: mirrors every push/tag to GitHub
- .forgejo/workflows/package.yml: builds on tag, publishes to Forgejo registry

Requires FORGEJO_TOKEN and GITHUB_MIRROR_TOKEN secrets in Forgejo.

packaging/arch/PKGBUILD

@@ -0,0 +1,32 @@
+# Maintainer: Breadway <rileyhorsham@gmail.com>
+
+pkgname=breadcrumbs
+pkgver=0.1.0
+pkgrel=1
+pkgdesc="Profile-aware Wi-Fi state machine with Tailscale integration"
+arch=('x86_64')
+url="https://github.com/Breadway/breadcrumbs"
+license=('MIT')
+depends=('networkmanager')
+optdepends=(
+  'tailscale: Tailscale VPN profile integration'
+)
+makedepends=('rust' 'cargo')
+source=("${pkgname}-${pkgver}.tar.gz")
+sha256sums=('SKIP')
+
+build() {
+  cd "${srcdir}/${pkgname}-${pkgver}"
+  cargo build --release --locked
+}
+
+check() {
+  cd "${srcdir}/${pkgname}-${pkgver}"
+  cargo test --release --locked
+}
+
+package() {
+  cd "${srcdir}/${pkgname}-${pkgver}"
+  install -Dm755 target/release/breadcrumbs "${pkgdir}/usr/bin/breadcrumbs"
+  install -Dm644 LICENSE "${pkgdir}/usr/share/licenses/${pkgname}/LICENSE"
+}