Tileset Selection: LoadTileImage: Tiles loaded

This covers the case where the rectangle is covered and these two scenarios:

1. The quality is alright --> return
2. The quality is not right --> look at existing tiles and if higher quality needed, go to parents. If lower quality needed, go to children.

Start by tracing the LoadTileImage entry point and how tileset selection currently handles a covered rectangle. Determine how existing tile quality is evaluated and how parent or child traversal is represented. Done means the selection returns when quality is sufficient and navigates to parents or children when it is not.

Written by the indexing model from the issue text.