Parallel batch loading + PrefabIndex + dynamic batch size

[HectorMu]

Summary

Replaces sequential one-by-one asset-bundle scanning with parallel batched loading, a lightweight prefab-name index, and several performance optimizations.

Changes (5 files, code only)

Parallel bundle loading (CarBuilder.cs — modified)

The core loading method was rewritten to support parallel batch processing:

• ThreadPool batches — ThreadPool.QueueUserWorkItem loads bundles in parallel, synchronized via ManualResetEvent. Overlaps disk I/O across bundles.
• 30-second timeout — prevents a single corrupted file from stalling startup; incomplete results are logged and skipped.
• Dynamic batch size — Math.Max(2, Environment.ProcessorCount) replaces the old hardcoded 4. Adapts to each user's core count automatically.
• Magic byte validation — reads the first 8 bytes of each file, checks for UnityFS/UnityRaw/UnityWeb headers before calling AssetBundle.LoadFromFile. Rejects non-bundles in microseconds instead of timing out.
• Bundle unloading — bundle.Unload(false) after extracting prefabs, freeing compressed data while keeping loaded GameObjects valid.
• Material array fix — renderer.materials captured once into a local variable instead of accessed repeatedly (avoided per-iteration array allocation).

Prefab name index (PrefabIndex.cs — NEW, ~120 lines)

A lightweight JSON index that avoids the expensive GetAllAssetNames() call for unchanged files:

• Key by path — maps each bundle file path to its last-write time + discovered prefab names.
• Up-to-date check — compares File.GetLastWriteTimeUtc ticks. If unchanged, prefab names are read from the index; GetAllAssetNames() is skipped entirely.
• Stale cleanup — after loading, entries for deleted or replaced files are removed from the index.
• Persistence — stored in Settings/prefab_index.json via JsonFx (same serializer already used by the project).

Much simpler than the previous CarCache approach — no signature hashing, no invalid-file tracking, no combined hash. Just a cached list of prefab names per file.

Assets.cs — cached reflection

AssetBundleBridge.AssetBundleType was calling Kernel.FindTypeByFullName() on every access (247+ times). The type and MethodInfo are now resolved once in the static constructor. The "Loaded asset bundle" log was also removed.

Section.cs + DictionaryExtensions.cs — factory overload for GetOrCreate

GetOrCreate<T>(string key, Func<T> factory) avoids allocating the default value when the key already exists. The extension method on Dictionary<string, object> mirrors the Section instance method.

ProfileCarColors.cs — use factory overload + cleanup

Switched all three GetOrCreate calls to the factory overload. Removed two LogInfo messages ("Assigning Profile Name...", "Assigning Vehicle Name...") that produced 500+ log lines at startup.