Add Linux desktop test build workflow

.github/workflows/linux-test-build.yml

@@ -0,0 +1,64 @@
+name: Build Linux Desktop Test Artifact
+
+"on":
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  build-linux:
+    name: Build Linux AppImage
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 20
+
+      - name: Set up Rust
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache Rust build
+        uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: frontends/desktop/src-tauri -> target
+
+      - name: Install Tauri Linux dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            libwebkit2gtk-4.1-dev \
+            libgtk-3-dev \
+            libayatana-appindicator3-dev \
+            librsvg2-dev \
+            patchelf
+
+      - name: Install desktop dependencies
+        working-directory: frontends/desktop
+        run: npm install
+
+      - name: Build Linux AppImage
+        working-directory: frontends/desktop
+        run: npm run tauri build -- --bundles appimage
+
+      - name: Collect Linux artifacts
+        shell: bash
+        run: |
+          set -euo pipefail
+          mkdir -p artifacts/linux
+          cp frontends/desktop/src-tauri/target/release/bundle/appimage/*.AppImage artifacts/linux/
+          cd artifacts/linux
+          sha256sum * > SHA256SUMS.txt
+          ls -lh
+
+      - name: Upload workflow artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: GenericAgent-Desktop-Linux-Test-${{ github.run_number }}
+          path: artifacts/linux/*
+          if-no-files-found: error