## What changed
- Probe the installed desktop app's update endpoint on macOS and Windows and report update-CDN reachability alongside the existing network diagnostics.
- Report newer Windows Store builds and macOS updates that Sparkle has staged for installation in the updates check and human-readable notes.
- Validate Windows update manifests against the production app identity, and use the persisted production appcast configuration when selecting the macOS feed.
## Testing
- Cover Windows version comparison and manifest identity validation.
- Cover macOS appcast selection and staged-bundle discovery.
- Verify the human-readable desktop update note.
GitOrigin-RevId: 1af5aa750144346b4b31f2b27a20371daf40d3c0
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