Fuzzy text search matching

For the following example structure, I can search:
- `MainGui` // 3 results

It would be nice if we could do fuzzy matching, like:
- `mgc` // shows MainGuiController

As an aside (maybe this should be a separte ticket): text filtering is only on filenames. It would be nice to filter on modules/packages. The following search gives 0 results:
- `src` // 0 results

No files, tests, or entry points are named. Start by locating the existing filename text-filtering implementation and trace how the tree search produces results; done means matching abbreviations such as `mgc` to `MainGuiController`, with the separate module/package filtering request clarified or split into another issue.

Written by the indexing model from the issue text.