feat: add ARM64 (aarch64) architecture support for builds and packages

Add cross-architecture build support so the project can be developed on
ARM64 (Fedora aarch64 laptop) while still producing amd64 packages for
production. All build, package, publish, and install scripts are now
architecture-aware via shared arch-helper.sh detection.

- Add scripts/arch-helper.sh for shared architecture detection
- CI builds both amd64 and arm64 in matrix strategy
- nfpm.yaml uses NFPM_ARCH env var instead of hardcoded amd64
- Build scripts support MCPCTL_TARGET_ARCH for cross-compilation
- installlocal.sh auto-detects RPM/DEB and filters by architecture
- release.sh gains --both-arches flag for dual-arch releases
- Package cleanup is arch-scoped (won't clobber other arch's packages)
- build-mcpd.sh supports --platform and --multi-arch flags
- Add pnpm scripts: rpm:build:amd64, deb:build:arm64, release:both
- Conditional rpm/dpkg-deb checks for cross-distro compatibility

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

installlocal.sh

@@ -1,23 +1,69 @@
 #!/bin/bash
-# Build (if needed) and install mcpctl RPM locally
+# Build (if needed) and install mcpctl locally.
+# Auto-detects package format: RPM for Fedora/RHEL, DEB for Debian/Ubuntu.
+#
+# Usage:
+#   ./installlocal.sh              # Build and install for native arch
+#   MCPCTL_TARGET_ARCH=amd64 ./installlocal.sh   # Cross-compile for amd64
 set -e
 
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 cd "$SCRIPT_DIR"
 
-RPM_FILE=$(ls dist/mcpctl-*.rpm 2>/dev/null | head -1)
+# Resolve target architecture
+source scripts/arch-helper.sh
+resolve_arch "${MCPCTL_TARGET_ARCH:-}"
 
-# Build if no RPM exists or if source is newer than the RPM
-if [[ -z "$RPM_FILE" ]] || [[ $(find src/ -name '*.ts' -newer "$RPM_FILE" 2>/dev/null | head -1) ]]; then
-    echo "==> Building RPM..."
-    bash scripts/build-rpm.sh
-    RPM_FILE=$(ls dist/mcpctl-*.rpm 2>/dev/null | head -1)
+# Detect package format
+if command -v rpm &>/dev/null && command -v dnf &>/dev/null; then
+  PKG_FORMAT="rpm"
+elif command -v dpkg &>/dev/null && command -v apt &>/dev/null; then
+  PKG_FORMAT="deb"
+elif command -v rpm &>/dev/null; then
+  PKG_FORMAT="rpm"
 else
-    echo "==> RPM is up to date: $RPM_FILE"
+  echo "Error: Neither rpm/dnf nor dpkg/apt found. Unsupported system."
+  exit 1
 fi
 
-echo "==> Installing $RPM_FILE..."
-sudo rpm -Uvh --force "$RPM_FILE"
+echo "==> Detected package format: $PKG_FORMAT (arch: $NFPM_ARCH)"
+
+# Find package matching the target architecture
+find_pkg() {
+  local pattern="$1"
+  # Filter by architecture name in filename
+  ls $pattern 2>/dev/null | grep -E "[._]${NFPM_ARCH}[._]" | head -1
+}
+
+if [ "$PKG_FORMAT" = "rpm" ]; then
+  PKG_FILE=$(find_pkg "dist/mcpctl-*.rpm")
+
+  # Build if no package exists or if source is newer
+  if [[ -z "$PKG_FILE" ]] || [[ $(find src/ -name '*.ts' -newer "$PKG_FILE" 2>/dev/null | head -1) ]]; then
+    echo "==> Building RPM..."
+    bash scripts/build-rpm.sh
+    PKG_FILE=$(find_pkg "dist/mcpctl-*.rpm")
+  else
+    echo "==> RPM is up to date: $PKG_FILE"
+  fi
+
+  echo "==> Installing $PKG_FILE..."
+  sudo rpm -Uvh --force "$PKG_FILE"
+else
+  PKG_FILE=$(find_pkg "dist/mcpctl*.deb")
+
+  # Build if no package exists or if source is newer
+  if [[ -z "$PKG_FILE" ]] || [[ $(find src/ -name '*.ts' -newer "$PKG_FILE" 2>/dev/null | head -1) ]]; then
+    echo "==> Building DEB..."
+    bash scripts/build-deb.sh
+    PKG_FILE=$(find_pkg "dist/mcpctl*.deb")
+  else
+    echo "==> DEB is up to date: $PKG_FILE"
+  fi
+
+  echo "==> Installing $PKG_FILE..."
+  sudo dpkg -i "$PKG_FILE" || sudo apt-get install -f -y
+fi
 
 echo "==> Reloading systemd user units..."
 systemctl --user daemon-reload