Adds macOS code signing and notarization infrastructure (FN-5609), introducing hardened runtime entitlements, electron-builder config for signed builds, and signing-enabled release workflows, with tests validating the configuration and docs covering the signing flow.
Fusion-Task-Id: FN-5609
Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>
Fusion-Task-Id: FN-5609
