TextBuffer history and clean-marker replay example

[Perchenko Anton (PerchAnton)]

Here is a small external example using Edit's actual TextBuffer at cb6de0a8: adapter, native controls and traces.

Three traces check Unicode byte positions, undo/redo and clean markers, plus CRLF normalization with set_crlf(false). All 15 steps and native controls pass on Windows and Linux. mark_as_clean does not save a file; the example does not drive the terminal UI or file dialogs.

I maintain interaction-check, the optional runner producing the step-level reports. This adds no dependency to Edit's release binary and is not a claim of missing upstream coverage. Would a community testing recipe using these public APIs be useful? Built and tested with Codex assistance.

[Dustin L. Howett (DHowett)]

I maintain interaction-check, the optional runner producing the step-level reports.

This sentence, and this entire issue, is less comprehensible than if I just grabbed 30 words from the dictionary at random and stuck them together.