Please add cursor support for editing

When i try and edit something in the request fields using my cursor all i get is A, B, C, D. This makes using wuzz really frustrating when I'm editing requests and trying different things. The same goes for the copy and paste issue.

Try using wuzz to play around with something like https://overthewire.org/wargames/natas/ and you'll see what i mean.

Start by running wuzz and reproducing the cursor-editing behavior in request fields, using the linked Natas example if useful. Trace the request-field editing entry point and verify that cursor movement and editing work as expected; clarify separately whether copy and paste belongs in the same change.

Written by the indexing model from the issue text.