Feat: overhaul to produce .dmg and .app on macOS build script

scripts/build-all.sh

@@ -229,6 +229,14 @@ bundle_plugins_native() {
     cargo xtask bundle "$PLUGIN_NAME" --release $tf
 }
 
+bundle_desktop_native() {
+    local platform="$1"
+    local tf
+    tf=$(target_flag "$platform")
+    # shellcheck disable=SC2086
+    cargo bundle --release --features desktop --bin cagire-desktop $tf
+}
+
 bundle_plugins_cross() {
     local platform="$1"
     local rd
@@ -300,6 +308,18 @@ copy_artifacts() {
         local dst="$OUT/cagire-desktop-${os}-${arch}${suffix}"
         cp "$src" "$dst"
         echo "    cagire-desktop -> $dst"
+
+        # macOS .app bundle
+        if [[ "$os" == "macos" ]]; then
+            local app_src="$rd/bundle/osx/Cagire.app"
+            if [[ -d "$app_src" ]]; then
+                local app_dst="$OUT/Cagire-${arch}.app"
+                rm -rf "$app_dst"
+                cp -R "$app_src" "$app_dst"
+                echo "    Cagire.app -> $app_dst"
+                scripts/make-dmg.sh "$app_dst" "$OUT"
+            fi
+        fi
     fi
 
     # AppImage for Linux targets
@@ -407,6 +427,10 @@ for platform in "${selected_platforms[@]}"; do
     if $build_desktop; then
         echo "  -> cagire-desktop"
         build_binary "$platform" --features desktop --bin cagire-desktop
+        if ! is_cross_target "$platform"; then
+            echo "  -> bundling cagire-desktop .app"
+            bundle_desktop_native "$platform"
+        fi
     fi
 
     if $build_plugins; then

scripts/make-dmg.sh

@@ -0,0 +1,52 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Usage: scripts/make-dmg.sh <app-path> <output-dir>
+# Produces a .dmg from a macOS .app bundle using only hdiutil.
+
+if [[ $# -ne 2 ]]; then
+    echo "Usage: $0 <app-path> <output-dir>"
+    exit 1
+fi
+
+APP_PATH="$1"
+OUTDIR="$2"
+REPO_ROOT="$(git rev-parse --show-toplevel)"
+
+if [[ ! -d "$APP_PATH" ]]; then
+    echo "ERROR: $APP_PATH is not a directory"
+    exit 1
+fi
+
+LIPO_OUTPUT=$(lipo -info "$APP_PATH/Contents/MacOS/cagire-desktop" 2>/dev/null)
+
+if [[ -z "$LIPO_OUTPUT" ]]; then
+    echo "ERROR: could not determine architecture from $APP_PATH"
+    exit 1
+fi
+
+if echo "$LIPO_OUTPUT" | grep -q "Architectures in the fat file"; then
+    ARCH="universal"
+else
+    ARCH=$(echo "$LIPO_OUTPUT" | awk '{print $NF}')
+    case "$ARCH" in
+        arm64) ARCH="aarch64" ;;
+    esac
+fi
+
+STAGING="$(mktemp -d)"
+trap 'rm -rf "$STAGING"' EXIT
+
+cp -R "$APP_PATH" "$STAGING/Cagire.app"
+ln -s /Applications "$STAGING/Applications"
+cp "$REPO_ROOT/assets/DMG-README.txt" "$STAGING/README.txt"
+
+DMG_NAME="Cagire-${ARCH}.dmg"
+mkdir -p "$OUTDIR"
+
+hdiutil create -volname "Cagire" \
+    -srcfolder "$STAGING" \
+    -ov -format UDZO \
+    "$OUTDIR/$DMG_NAME"
+
+echo "  DMG -> $OUTDIR/$DMG_NAME"