feat(packaging): add self-contained AppImage build (x86_64 + aarch64) (#573)

* feat(packaging): add self-contained AppImage build

Bundles the wheel plus PyGObject/GTK3/AppIndicator/IBus typelibs into a
relocatable x86_64 AppImage via linuxdeploy + linuxdeploy-plugin-gtk, so
users get a zero-install, no-sandbox-negotiation alternative alongside
AUR/PyPI. Wired into nightly and tagged releases, plus a smoke-test job
in the PR pipeline since AppImage/ELF bundling can't be verified on a
macOS dev machine.

* feat(packaging): add aarch64 AppImage builds

Parameterizes build.sh on uname -m instead of hardcoding x86_64 (both
linuxdeploy and appimagetool publish aarch64 continuous builds, and
pywhispercpp ships manylinux_aarch64 wheels, so no from-source compile
needed). Adds an arch matrix to the PR smoke-test job, and a second
job in nightly.yml/release.yml that builds on GitHub's free
ubuntu-24.04-arm hosted runner and attaches the aarch64 AppImage to
the same release the x86_64 job already created.

.github/workflows/release.yml

@@ -29,6 +29,21 @@ jobs:
           python-version: ${{ env.PYTHON_VERSION }}
           cache: 'pip'
 
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            portaudio19-dev \
+            python3-dev \
+            libgirepository1.0-dev \
+            libgirepository-2.0-dev \
+            pkg-config \
+            libcairo2-dev \
+            gobject-introspection \
+            gir1.2-gtk-3.0 \
+            gir1.2-appindicator3-0.1 \
+            gir1.2-ibus-1.0
+
       - name: Install build dependencies
         run: |
           python -m pip install --upgrade pip
@@ -59,6 +74,11 @@ jobs:
           echo "Built packages:"
           ls -la dist/
 
+      - name: Build AppImage (x86_64)
+        run: |
+          bash packaging/appimage/build.sh dist/*.whl "${{ steps.get_version.outputs.VERSION }}" dist
+          ls -la dist/*.AppImage
+
       - name: Create Release
         id: create_release
         uses: softprops/action-gh-release@v2
@@ -66,6 +86,7 @@ jobs:
           files: |
             dist/*.whl
             dist/*.tar.gz
+            dist/*.AppImage
           generate_release_notes: true
           draft: false
           prerelease: ${{ contains(github.ref, 'alpha') || contains(github.ref, 'beta') || contains(github.ref, 'rc') }}
@@ -103,9 +124,77 @@ jobs:
             yay -S vocalinux
             ```
 
+            ### AppImage (no install, no root)
+            Download the `.AppImage` matching your CPU (`x86_64` or `aarch64`, the latter attached
+            shortly after this release is published) below:
+            ```bash
+            chmod +x Vocalinux-${{ steps.get_version.outputs.VERSION }}-x86_64.AppImage
+            ./Vocalinux-${{ steps.get_version.outputs.VERSION }}-x86_64.AppImage
+            ```
+            Still requires `xdotool`/`wtype`/`ydotool` on the host for text injection, same as the PyPI path.
+
             ---
             See [CHANGELOG](https://github.com/jatinkrmalik/vocalinux/releases) for detailed changes.
 
+  build-appimage-arm64:
+    name: Build and Attach AppImage (aarch64)
+    needs: build-and-release
+    runs-on: ubuntu-24.04-arm
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ env.PYTHON_VERSION }}
+          cache: 'pip'
+
+      - name: Install system dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            portaudio19-dev \
+            python3-dev \
+            libgirepository1.0-dev \
+            libgirepository-2.0-dev \
+            pkg-config \
+            libcairo2-dev \
+            gobject-introspection \
+            gir1.2-gtk-3.0 \
+            gir1.2-appindicator3-0.1 \
+            gir1.2-ibus-1.0
+
+      - name: Install build dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install build wheel setuptools
+
+      - name: Extract version from tag
+        id: get_version
+        run: |
+          VERSION=${GITHUB_REF#refs/tags/v}
+          echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
+
+      - name: Build package
+        run: |
+          python -m build
+          ls -la dist/
+
+      - name: Build AppImage (aarch64)
+        run: |
+          bash packaging/appimage/build.sh dist/*.whl "${{ steps.get_version.outputs.VERSION }}" dist
+          ls -la dist/*.AppImage
+
+      - name: Attach to release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh release upload "${{ github.ref_name }}" \
+            dist/*.AppImage \
+            --repo ${{ github.repository }} \
+            --clobber
+
   publish-pypi:
     name: Publish to PyPI
     needs: build-and-release