fix(release): add RUSTFLAGS to suppress dead_code warnings in desktop build

- Add RUSTFLAGS environment variable with "-A dead_code" flag to the Windows desktop build job
- This suppresses dead code warnings during Rust compilation of the Tauri desktop app

Author: craftslab

.github/workflows/ai-codespark-release.yml

@@ -174,6 +174,8 @@ jobs:
 
       - name: Build desktop app
         working-directory: packages/desktop
+        env:
+          RUSTFLAGS: "-A dead_code"
         run: |
           bun run build
           bun tauri build --bundles nsis