Fix desktop release workflow: macOS code signing and Linux webkit2gtk dep

- Disable code signing for CI macOS builds (ad-hoc signing)
- Add libwebkit2gtk-4.1-dev to Linux build dependencies

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: benkaiser

.github/workflows/release.yml

@@ -17,6 +17,10 @@ jobs:
         with:
           channel: stable
       - run: flutter pub get
+      - name: Disable code signing for CI
+        run: |
+          sed -i '' 's/CODE_SIGN_IDENTITY = "Apple Development";/CODE_SIGN_IDENTITY = "-";/' macos/Runner.xcodeproj/project.pbxproj
+          sed -i '' 's/CODE_SIGN_STYLE = Automatic;/CODE_SIGN_STYLE = Manual;/' macos/Runner.xcodeproj/project.pbxproj
       - run: flutter build macos --release
       - name: Zip macOS app
         run: |
@@ -55,7 +59,7 @@ jobs:
       - name: Install Linux build dependencies
         run: |
           sudo apt-get update
-          sudo apt-get install -y cmake ninja-build pkg-config libgtk-3-dev liblzma-dev libstdc++-12-dev
+          sudo apt-get install -y cmake ninja-build pkg-config libgtk-3-dev liblzma-dev libstdc++-12-dev libwebkit2gtk-4.1-dev
       - run: flutter pub get
       - run: flutter build linux --release
       - name: Create tar.gz archive