Adds three Bindless variants (GetOrUploadBindless,
GetOrUploadWithOrigTextureOverrideBindless,
GetOrUploadWithPaletteOverrideBindless) that decode + upload via
UploadRgba8AsLayer1Array (Texture2DArray) and cache in three new
dictionaries that mirror the legacy three-cache structure. Each entry
stores both the GL texture name (for Dispose cleanup in Task 4) and
the resident bindless handle.
Constructor gains optional BindlessSupport param; null keeps backward
compat. EnsureBindlessAvailable throws InvalidOperationException if
Bindless* methods are called without BindlessSupport (fail-fast vs
silent zero handle that would produce GPU faults).
Dispose extended to make handles non-resident before deleting the
underlying Texture2DArray names (bindless handles must be made
non-resident before the texture is deleted; skipping this causes
GPU faults on driver cleanup).
Marker test in TextureCacheBindlessTests documents the throw contract
for future engineers; real bindless integration is verified at
Task 14's visual gate.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
