feat: add texture diagnostics to viewer

README.md

@@ -119,6 +119,7 @@ All files are uploaded to `VF/` (not just diffs), because the move operation emp
 - The server applies a lightweight per-folder lock on Drive and Git routes to avoid duplicate commits and concurrent writes
 - The folder is staged server-side so the browser sends the payload only once during the full upload flow
 - Invalid `model.gltf` JSON or malformed `buffers` entries block the upload before remote writes
+- The client shows texture diagnostics before upload: missing GLTF image files, unsupported texture formats, duplicate flat filenames, unused textures, broad opacity maps, and all-transparent material exports
 - Git LFS uploads are batched in groups of 100 objects to stay within the LFS Batch API limit
 
 ### Commit messages
@@ -188,6 +189,7 @@ components/
 │   ├── FolderCard.tsx         # Folder status card (Drive + Git)
 │   ├── DriveStatusLine.tsx    # Drive/Git status sub-line
 │   ├── WarningBanner.tsx      # Missing texture warnings
+│   ├── TextureDiagnosticsPanel.tsx # Texture loading/export diagnostics
 │   ├── OverwriteConfirmModal.tsx  # Diff confirmation dialog
 │   ├── NoChangesModal.tsx     # "No changes detected" dialog
 │   ├── DriveErrorModal.tsx    # "Drive failed, continue?" dialog