Update PKGBUILD versions and add AUR test scripts

- Update pkgver fallback to 4.2.1 in all PKGBUILDs
- Add test-aur-build.sh for Docker-based testing
- Add test-aur-nspawn.sh for systemd-nspawn testing

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

test-aur-build.sh

@@ -0,0 +1,107 @@
+#!/bin/bash
+# Test AUR package builds in a clean Arch container
+#
+# Usage: sudo ./test-aur-build.sh [package]
+#   package: all (default), full, cli, api
+
+set -e
+
+PACKAGE="${1:-all}"
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+
+echo "=== Stegasoo AUR Build Test ==="
+echo "Package: $PACKAGE"
+echo ""
+
+# Create a test script to run inside container
+cat > /tmp/aur-build-test.sh << 'INNERSCRIPT'
+#!/bin/bash
+set -e
+
+# Update system
+pacman -Syu --noconfirm
+
+# Install build dependencies
+pacman -S --noconfirm --needed \
+    base-devel git python python-build python-hatchling \
+    zbar
+
+# Create build user (makepkg won't run as root)
+useradd -m builder
+echo "builder ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
+
+# Copy source to build location
+cp -r /src /home/builder/stegasoo
+chown -R builder:builder /home/builder/stegasoo
+
+build_package() {
+    local pkg_dir="$1"
+    local pkg_name="$2"
+
+    echo ""
+    echo "=========================================="
+    echo "Building: $pkg_name"
+    echo "=========================================="
+
+    cd "/home/builder/stegasoo/$pkg_dir"
+
+    # Build as non-root user
+    sudo -u builder makepkg -sf --noconfirm
+
+    # Show result
+    ls -lh *.pkg.tar.zst
+
+    # Test install
+    echo "Installing $pkg_name..."
+    pacman -U --noconfirm *.pkg.tar.zst
+
+    # Quick test
+    echo "Testing $pkg_name..."
+    stegasoo --version
+    stegasoo --help | head -20
+
+    # Uninstall for next test
+    pacman -R --noconfirm "${pkg_name%-git}" 2>/dev/null || pacman -R --noconfirm "$pkg_name" 2>/dev/null || true
+
+    echo "$pkg_name: SUCCESS"
+}
+
+case "$1" in
+    full)
+        build_package "aur" "stegasoo-git"
+        ;;
+    cli)
+        build_package "aur-cli" "stegasoo-cli-git"
+        ;;
+    api)
+        build_package "aur-api" "stegasoo-api-git"
+        ;;
+    all)
+        build_package "aur" "stegasoo-git"
+        build_package "aur-cli" "stegasoo-cli-git"
+        build_package "aur-api" "stegasoo-api-git"
+        ;;
+    *)
+        echo "Unknown package: $1"
+        exit 1
+        ;;
+esac
+
+echo ""
+echo "=========================================="
+echo "All builds completed successfully!"
+echo "=========================================="
+INNERSCRIPT
+
+chmod +x /tmp/aur-build-test.sh
+
+# Run in Arch container
+echo "Starting Arch container..."
+docker run --rm -it \
+    -v "$SCRIPT_DIR:/src:ro" \
+    -v "/tmp/aur-build-test.sh:/build.sh:ro" \
+    archlinux:latest \
+    /bin/bash -c "chmod +x /build.sh && /build.sh $PACKAGE"
+
+echo ""
+echo "=== Build test complete ==="