Return a copy of installedmods, enginebuilds and modtools instead of references (C4 fix)

[Shivansps]

File: Knossos.NET/Classes/Knossos.cs:25-27

private static List<Mod> installedMods = new List<Mod>();
private static List<FsoBuild> engineBuilds = new List<FsoBuild>();
private static List<Tool> modTools = new List<Tool>();

These are accessed from multiple threads (UI, background tasks, Nebula loading, install tasks) with zero synchronization -- there are no lock statements anywhere in the codebase. GetInstalledModList(null) and GetInstalledBuildsList() return the raw list references, allowing callers to mutate them (e.g., App.axaml.cs calls mods.Sort() on the shared list). Concurrent read+write on List<T> causes InvalidOperationException, IndexOutOfRangeException, or silent corruption.

This should be enoght to make sure it cant happen, when the entire list is returned, a copy is sent instead of a reference.