Add minimum update age setting to filter recent package updates

[Gabriel Dufresne (GabrielDuf)]

Summary

• Adds a global "minimum update age" setting (Updates page) that hides package updates released less than a specified number of days ago, protecting against supply chain attacks
• Adds per-manager overrides for the same setting in each package manager's settings page
• Both settings support preset values (1, 3, 7, 14, 30 days) and a "Custom..." option that reveals a numeric-only text input

Details

• Filtering is applied in UpgradablePackagesLoader.IsPackageValid() using IPackageDetails.UpdateDate; packages whose release date cannot be determined are shown regardless (fail-open)
• A compatibility table on the Updates settings page shows which package managers expose release dates
• Per-manager setting can defer to the global value, explicitly disable the filter, or set its own threshold