Add Gitea Actions workflow to build AppImage on tag

Builds the Linux AppImage on a v* tag, runs the test suite first, and
attaches the artifact to a Gitea release via the API (no third-party
action, so nothing needs to be fetched from github.com at runtime).

Guards that the tag matches package.json version: electron-builder names
the artifact from package.json, so tagging v1.0.1 without bumping the
manifest would otherwise publish an AppImage named 1.0.0.

Requires a RELEASE_TOKEN secret and a registered act_runner; neither is
set up yet, so this is inert until both exist.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -0,0 +1,72 @@
+name: Build AppImage
+
+# Builds the Linux AppImage on a version tag and attaches it to a Gitea release.
+# Tag must match the version in desktop-client/package.json, since electron-builder
+# names the artifact from package.json (not from the tag).
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+
+jobs:
+  appimage:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: desktop-client
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+
+      - name: Verify tag matches package.json version
+        if: startsWith(github.ref, 'refs/tags/v')
+        run: |
+          pkg_version=$(node -p "require('./package.json').version")
+          tag_version="${GITHUB_REF_NAME#v}"
+          if [ "$pkg_version" != "$tag_version" ]; then
+            echo "Tag $GITHUB_REF_NAME does not match package.json version $pkg_version." >&2
+            echo "Bump package.json before tagging, or the AppImage will be misnamed." >&2
+            exit 1
+          fi
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Run tests
+        run: npm test
+
+      - name: Build AppImage
+        run: npx electron-builder --linux AppImage --publish never
+
+      - name: Attach AppImage to release
+        if: startsWith(github.ref, 'refs/tags/v')
+        env:
+          TOKEN: ${{ secrets.RELEASE_TOKEN }}
+          API: ${{ github.server_url }}/api/v1/repos/${{ github.repository }}
+        run: |
+          set -euo pipefail
+          artifact=$(ls dist/*.AppImage | head -1)
+          echo "Publishing $artifact for $GITHUB_REF_NAME"
+
+          # Reuse the release if the tag already has one, otherwise create it.
+          release_id=$(curl -sf -H "Authorization: token $TOKEN" \
+            "$API/releases/tags/$GITHUB_REF_NAME" | node -p \
+            "JSON.parse(require('fs').readFileSync(0,'utf8')).id" 2>/dev/null || true)
+
+          if [ -z "${release_id:-}" ]; then
+            release_id=$(curl -sf -X POST -H "Authorization: token $TOKEN" \
+              -H "Content-Type: application/json" \
+              -d "{\"tag_name\":\"$GITHUB_REF_NAME\",\"name\":\"$GITHUB_REF_NAME\"}" \
+              "$API/releases" | node -p \
+              "JSON.parse(require('fs').readFileSync(0,'utf8')).id")
+          fi
+
+          curl -sf -X POST -H "Authorization: token $TOKEN" \
+            -F "attachment=@$artifact" \
+            "$API/releases/$release_id/assets?name=$(basename "$artifact")" \
+            -o /dev/null
+          echo "Attached $(basename "$artifact") to release $release_id"

desktop-client/package.json

@@ -26,7 +26,15 @@
       "sign": false,
       "signAndEditExecutable": false,
       "certificateSubjectName": null
-    }
+    },
+    "linux": {
+      "target": ["AppImage"],
+      "icon": "build/icon.png",
+      "category": "AudioVideo",
+      "synopsis": "YouTube Music player with a now-playing overlay for OBS",
+      "maintainer": "What's That Music"
+    },
+    "artifactName": "${productName}-${version}-${arch}.${ext}"
   },
   "dependencies": {
     "express": "^5.2.1",