build mac releases for both intel and apple silicon

The mac dmg was previously built only on macos-13 (an Intel runner),
so releases only ran natively on Intel Macs and required Rosetta 2 on
Apple Silicon. cx_Freeze can only build for the host architecture, so
this adds a build matrix with macos-14 (arm64) alongside macos-13 (x64),
and adds ${arch} to the mac artifact name so the two dmgs don't collide.

Build-tested natively on an M2 Mac (macOS 26.5): frontend, cx_Freeze
backend, and electron-builder dmg all build and run natively.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

.github/workflows/build.yml

@@ -45,7 +45,12 @@ jobs:
           artifacts: "dist/*-win-installer.exe,dist/*-win-portable.exe"
 
   build_mac:
-    runs-on: macos-13
+    strategy:
+      matrix:
+        # macos-13 is an Intel (x64) runner, macos-14 is an Apple Silicon (arm64) runner.
+        # cx_Freeze can only build for the host architecture, so each arch needs its own runner.
+        os: [macos-13, macos-14]
+    runs-on: ${{ matrix.os }}
     permissions:
       contents: write
     steps:
@@ -80,7 +85,7 @@ jobs:
           replacesArtifacts: true
           omitDraftDuringUpdate: true
           omitNameDuringUpdate: true
-          artifacts: "dist/*-mac.dmg"
+          artifacts: "dist/*-mac-*.dmg"
 
   build_linux:
     runs-on: ubuntu-latest

package.json

@@ -33,7 +33,7 @@
     "mac": {
       "target": "dmg",
       "identity": null,
-      "artifactName": "ReticulumMeshChat-v${version}-${os}.${ext}",
+      "artifactName": "ReticulumMeshChat-v${version}-${os}-${arch}.${ext}",
       "extendInfo": {
         "NSMicrophoneUsageDescription": "Microphone access is only needed for Audio Calls",
         "com.apple.security.device.audio-input": true