Add multi-platform build scripts

- build-rpm.sh: Build RPM packages on RHEL/CentOS/Fedora
- build-alpine.sh: Build APK packages on Alpine Linux
- build-arch.sh: Build Arch packages on Arch Linux/Manjaro

Each script can also run in Docker containers for cross-platform builds.
Complements CI/CD pipeline for local package building.

build-alpine.sh

@@ -0,0 +1,72 @@
+#!/bin/bash
+# Build Alpine Package (.apk)
+# Run on: Alpine Linux 3.18+
+# Or in Docker: docker run -v $(pwd):/build alpine:latest /build/build-alpine.sh
+
+set -e
+
+echo "=== Linux Patch API - Alpine Build Script ==="
+echo ""
+
+# Check if running on Alpine
+if ! command -v abuild &> /dev/null; then
+    echo "Installing Alpine build tools..."
+    apk add --no-cache alpine-sdk rust cargo openssl-dev systemd-dev git
+fi
+
+# Setup build environment
+echo "Setting up build environment..."
+export CBUILDROOT=$(pwd)/.abuild
+mkdir -p "$CBUILDROOT"
+
+# Build release binary
+echo "Building release binary..."
+cargo build --release --target x86_64-unknown-linux-musl
+
+# Create package directory
+PKGDIR=$(pwd)/apk-package
+mkdir -p "$PKGDIR"/usr/bin
+mkdir -p "$PKGDIR"/etc/linux_patch_api
+mkdir -p "$PKGDIR"/lib/systemd/system
+
+# Copy files
+cp target/x86_64-unknown-linux-musl/release/linux-patch-api "$PKGDIR"/usr/bin/
+chmod 755 "$PKGDIR"/usr/bin/linux-patch-api
+cp configs/linux-patch-api.service "$PKGDIR"/lib/systemd/system/
+cp configs/config.yaml.example "$PKGDIR"/etc/linux_patch_api/config.yaml
+cp configs/whitelist.yaml.example "$PKGDIR"/etc/linux_patch_api/whitelist.yaml
+
+# Create APKBUILD
+echo "Creating APKBUILD..."
+cat > APKBUILD << 'EOF'
+pkgname=linux-patch-api
+pkgver=1.0.0
+pkgrel=1
+pkgdesc="Secure remote package management API for Linux systems"
+url="https://gitea.internal/linux-patch-api"
+arch="x86_64"
+license="MIT"
+depends="systemd"
+source="apk-package"
+
+package() {
+    cp -r "$srcdir"/apk-package/* "$pkgdir"/
+}
+EOF
+
+# Build APK package
+echo "Building APK package..."
+abuild -F -r
+
+# Copy to releases directory
+echo ""
+echo "Copying package to releases/..."
+mkdir -p releases
+cp ~/packages/x86_64/*.apk releases/ 2>/dev/null || cp /root/packages/x86_64/*.apk releases/ || find / -name "linux-patch-api-*.apk" -exec cp {} releases/ \; 2>/dev/null || true
+
+echo ""
+echo "=== Build Complete ==="
+echo "Package: releases/linux-patch-api-*.apk"
+echo ""
+echo "Install with:"
+echo "  sudo apk add --allow-unstable ./releases/linux-patch-api-*.apk"