Ship S2 fixes: structural anchors are not mounts, mod presets refused, one bad mod never bricks the boot

- Validate: a hardpoint's anchor role is fixed by its type (thruster-emitter, radiator-mesh, else articulation); ShipModPlan's
  duplicate role check is deleted.
- Loadouts.Commit refuses a preset naming a mod design (mod-hull:/mod-ship:), so the shipped catalog never references a mod.
- Compose quarantines each package: a bad package is excluded and named, a collision excludes every package involved; the
  game boots on the rest (or the shipped catalog) and the main menu lists the exclusions.
- RequireDesigns refuses a save with a null item or lot instead of throwing NullReferenceException.
- Tests: per structural role, muzzle id ties, every slot/zone/lot in RequireDesigns, listing order, exclusion cases.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Assets/Scripts/ServerShared/Loadout.cs

@@ -64,11 +64,14 @@ public static class Loadouts
     // The only writer of presets. It opens its own short-lived cache over the catalog file, writable, and disposes it
     // after the one commit. No other cache is touched, so no catalog instance play holds (or has mutated) can reach the
     // file; a cache that already has the catalog open sees the preset only once it reloads.
-    // Throws and writes nothing when the file is missing (capture never creates a catalog), when a preset of this name
+    // Throws and writes nothing when the loadout names a mod design (hull or slot), when the file is missing (capture never creates a catalog), when a preset of this name
     // exists under another key, or when one exists under KeyOf(Name) and replace is not set. The commit is conditional
     // on the record at KeyOf(Name), so a preset changed on disk since this open is not clobbered: returns false then.
     public static bool Commit(string catalogPath, Loadout loadout, bool replace)
     {
+        var modDesigns = new[] { loadout.Hull.Key }.Concat(loadout.Slots.Select(slot => slot.Design.Key)).Where(ShipModCatalog.IsModKey).Select(key => key.Value).Distinct().ToArray();
+        if (modDesigns.Length > 0)
+            throw new InvalidOperationException($"Preset '{loadout.Name}' names mod designs ({string.Join(", ", modDesigns)}); the shipped catalog never references a mod, so a mod ship cannot be captured as a preset.");
         if (!File.Exists(catalogPath))
             throw new InvalidOperationException($"Catalog {catalogPath} does not exist; a preset capture never creates one.");
         using var cache = AetheriaStores.Open(catalogPath, catalogWritable: true);