feat: add Arch Linux package (PKGBUILD, systemd service, sysusers)

- PKGBUILD for building the package
- Systemd service with CAP_NET_BIND_SERVICE for port 53
- sysusers.d config to create doh-forwarder system user
- Default config at /etc/doh-forwarder/config.toml

pkg/arch/PKGBUILD

@@ -0,0 +1,46 @@
+# Maintainer: Mohammadreza Khani <mohamadreza.khani@proton.me>
+pkgname=doh-forwarder
+pkgver=0.1.0
+pkgrel=1
+pkgdesc="A lightweight DNS-over-HTTPS forwarder"
+arch=('x86_64')
+url="https://gitea.logi.camp/LogiCrew/doh-forwarder"
+license=('MIT')
+depends=('gcc-libs')
+makedepends=('rust' 'cargo')
+backup=('etc/doh-forwarder/config.toml')
+source=("$pkgname-$pkgver.tar.gz::https://git.logicamp.dev/LogiCrew/doh-forwarder/archive/v${pkgver}.tar.gz"
+        'doh-forwarder.service'
+        'doh-forwarder.sysusers'
+        'doh-forwarder.conf')
+sha256sums=('SKIP'
+            'SKIP'
+            'SKIP'
+            'SKIP')
+
+build() {
+    cd "$pkgname"
+    cargo build --release --locked
+}
+
+check() {
+    cd "$pkgname"
+    cargo test --release --locked
+}
+
+package() {
+    cd "$pkgname"
+
+    # Binary
+    install -Dm755 "target/release/doh-forwarder" "$pkgdir/usr/bin/doh-forwarder"
+
+    # Config
+    install -Dm644 "$srcdir/doh-forwarder.conf" "$pkgdir/etc/doh-forwarder/config.toml"
+
+    # Systemd
+    install -Dm644 "$srcdir/doh-forwarder.service" "$pkgdir/usr/lib/systemd/system/doh-forwarder.service"
+    install -Dm644 "$srcdir/doh-forwarder.sysusers" "$pkgdir/usr/lib/sysusers.d/doh-forwarder.conf"
+
+    # License
+    install -Dm644 LICENSE "$pkgdir/usr/share/licenses/$pkgname/LICENSE"
+}