Switch engine asset references from Resources paths to Addressables GUIDs

Cut 2 of docs/addressables-cut.md. The asset move (git mv
Resources/{Prefabs,Schematics,Sprites/Icons} -> Content/...) and the
UnityHelpers.cs deletion already landed in 1fdf8151, picked up by a
concurrent session sharing this working tree; this commit is the rest
of Cut 2 landing on top of that shared state, atomically:

- Bump CultLib to cultlib-unity-v1.0.60 / caching-unity-v1.4.0 (both
  45c2f40) in Packages/manifest.json, packages-lock.json and
  Directory.Build.props, together with the 8 ServerShared
  [CultInspectorAssetPath] usages becoming [CultInspectorAssetGuid] -
  the .NET and Unity sides move together or nothing compiles.
- Assets/Scripts/EngineAssets.cs replaces UnityHelpers: loads an
  Addressables key (bare GUID or guid[subAsset]) synchronously,
  loading the GameObject and taking the component for the four sites
  that load a component. ActionBarSlot, EntityInstance, ShipInstance
  and ZoneRenderer call it instead of Resources.Load/UnityHelpers; the
  inline "Assets/Resources/" prefix strips are gone with them.
  CultCacheDrawers' schematic preview goes through
  AssetDatabase.GUIDToAssetPath first.
- Assets/Scripts/Editor/EngineAssetCheck.cs validates every stored
  [CultInspectorAssetGuid] value: 32 lowercase hex, resolves to a file,
  is addressable, and satisfies its member's consumer-type contract
  (Texture2D for icons/logos/schematics, a GameObject with the right
  component for prefabs) - table-driven, so an attributed member with
  no row fails loudly instead of being skipped.
- GameData/Aetheria.cc: the scratch migration (Aetheria.Shared + the
  pinned CultLib revision, a throwaway console app, never landed)
  walked all 138 attributed field slots across 180 documents,
  rewriting the 30 non-empty Resources paths to their .meta GUIDs -
  108 stayed empty, 0 unresolved, matching the map's census exactly.

Verification: dotnet test tests/Aetheria.Shared.Tests 61/61 green
against CultLib 45c2f40; Unity 6000.3.24f1 batchmode compiles clean;
EngineAssetCheck.Run passes all 30 stored references; the map's
negative greps are clean; tests/mutation_tests.py's 5 mutations (wrong
type, non-addressable, random guid, an old path, and an untabled
attributed member) are all caught and named, the control case and the
post-revert recompile stay clean, and the catalog/source are restored
byte-identical afterward.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Packages/manifest.json

@@ -51,8 +51,8 @@
     "com.unity.modules.vr": "1.0.0",
     "com.unity.modules.wind": "1.0.0",
     "com.unity.modules.xr": "1.0.0",
-    "org.gamecult.caching.unity": "https://github.com/GameCult/CultLib.git?path=/src/GameCult.Unity/Assets/Caching#caching-unity-v1.3.1",
-    "org.gamecult.cultlib": "https://github.com/GameCult/CultLib.git?path=/unity/org.gamecult.cultlib#cultlib-unity-v1.0.59",
+    "org.gamecult.caching.unity": "https://github.com/GameCult/CultLib.git?path=/src/GameCult.Unity/Assets/Caching#caching-unity-v1.4.0",
+    "org.gamecult.cultlib": "https://github.com/GameCult/CultLib.git?path=/unity/org.gamecult.cultlib#cultlib-unity-v1.0.60",
     "org.gamecult.cultmath": "https://github.com/GameCult/CultLib.git?path=/packages/cultmath/unity/org.gamecult.cultmath#cultmath-unity-v0.2.3"
   }
 }

Packages/packages-lock.json

@@ -243,20 +243,20 @@
       "url": "https://packages.unity.com"
     },
     "org.gamecult.caching.unity": {
-      "version": "https://github.com/GameCult/CultLib.git?path=/src/GameCult.Unity/Assets/Caching#caching-unity-v1.3.1",
+      "version": "https://github.com/GameCult/CultLib.git?path=/src/GameCult.Unity/Assets/Caching#caching-unity-v1.4.0",
       "depth": 0,
       "source": "git",
       "dependencies": {
-        "org.gamecult.cultlib": "1.0.59"
+        "org.gamecult.cultlib": "1.0.60"
       },
-      "hash": "a0813c6eed24d30bf88073ef615b633c77ebfcd6"
+      "hash": "45c2f4006f5f7dab357426cabd3197e8d0a17f66"
     },
     "org.gamecult.cultlib": {
-      "version": "https://github.com/GameCult/CultLib.git?path=/unity/org.gamecult.cultlib#cultlib-unity-v1.0.59",
+      "version": "https://github.com/GameCult/CultLib.git?path=/unity/org.gamecult.cultlib#cultlib-unity-v1.0.60",
       "depth": 0,
       "source": "git",
       "dependencies": {},
-      "hash": "a0813c6eed24d30bf88073ef615b633c77ebfcd6"
+      "hash": "45c2f4006f5f7dab357426cabd3197e8d0a17f66"
     },
     "org.gamecult.cultmath": {
       "version": "https://github.com/GameCult/CultLib.git?path=/packages/cultmath/unity/org.gamecult.cultmath#cultmath-unity-v0.2.3",