NF: tools/text2filetree.py helper to convert some indented text into our filetree example spec

[yarikoptic]

See included within script tests

It was produced pretty much fully by just interacting with Claude . chatgpt got stuck on inability to run tests itself (although it did try!).

Original demand came while working on

• [ENH] microelectrode electrophysiology specification (BEP032) #1705

while transferring examples from google doc (yet to actually use the script on them fully ;) )

[effigies]

It seems like a problem that we're round-tripping a text tree into a Python dict and back. It looks like (#807, #837) the goal was just to convert to tree-style and use it consistently.

I don't think the dict approach is very pleasant, and I assume that's why this tool was desired, so I wonder if it would be better to make a custom fence (a la #1794):

```filetree
root
  subdir1
    file1.txt
    subsubdir
      file2.txt
  subdir2
    file3.txt
```

And convert that to:

<pre>
root
├── subdir1
│   ├── file1.txt
│   └── subsubdir
│       └── file2.txt
└── subdir2
    └── file3.txt
</pre>

We could also handle creating a tree from a list of files, e.g.:

```filetree
root/subdir1/file1.txt
root/subdir1/subsubdir/file2.txt
root/subdir2/file3.txt
```