feat(ci): add GitHub Action job to publish Snap on tags

Add a publish-snap job to the CI workflow that runs after build and
only triggers for version tags (refs/tags/v*). The job downloads the
linux build artifacts, installs snapcraft, locates the generated .snap
file and uploads it to the Snapcraft Store releasing to the stable
channel. It validates the presence of a snap file and fails if none is
found.

This enables automated Snap distribution for tagged releases using the
SNAPCRAFT_STORE_CREDENTIALS secret.

.github/workflows/build-and-make.yaml

@@ -72,16 +72,16 @@ jobs:
             - name: Build backend
               run: npm run build:backend
 
-            - name: Override macOS arch in package.json
+            - name: Override macOS arch in electron-builder.json
               if: matrix.os == 'macos'
               run: |
-                # Replace the mac arch array with just the target architecture
-                node -e "
-                  const fs = require('fs');
-                  const pkg = JSON.parse(fs.readFileSync('package.json', 'utf8'));
-                  pkg.build.mac.target.arch = ['${{ matrix.arch }}'];
-                  fs.writeFileSync('package.json', JSON.stringify(pkg, null, 4));
-                "
+                  # Replace the mac arch array with just the target architecture
+                  node -e "
+                    const fs = require('fs');
+                    const pkg = JSON.parse(fs.readFileSync('electron-builder.json', 'utf8'));
+                    pkg.mac.target.arch = ['${{ matrix.arch }}'];
+                    fs.writeFileSync('electron-builder.json', JSON.stringify(pkg, null, 4));
+                  "
 
             - name: Make Electron app
               run: npm run make:app
@@ -170,3 +170,31 @@ jobs:
                       artifacts/windows-artifacts/*.zip
               env:
                   GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+    publish-snap:
+        name: Publish to Snapcraft Store
+        needs: build
+        runs-on: ubuntu-latest
+        # if: startsWith(github.ref, 'refs/tags/v') # Only publish on version tags
+
+        steps:
+            - name: Download snap artifact
+              uses: actions/download-artifact@v4
+              with:
+                  name: linux-artifacts
+                  path: artifacts
+
+            - name: Setup Snapcraft
+              uses: samuelmeuli/action-snapcraft@v3
+              env:
+                  SNAPCRAFT_STORE_CREDENTIALS: ${{ secrets.snapcraft_token }}
+
+            - name: Publish all snaps to edge channel
+              run: |
+                  # Find and publish all snap files
+                  for SNAP_FILE in artifacts/*.snap; do
+                      if [ -f "$SNAP_FILE" ]; then
+                          echo "Publishing: $SNAP_FILE"
+                          snapcraft upload --release=edge "$SNAP_FILE"
+                      fi
+                  done