docs: add macOS Terminal backspace troubleshooting to README

[stephenlzc]

Summary

Add a Troubleshooting section to the README documenting the macOS Terminal.app backspace compatibility issue (#234).

Problem

macOS Terminal.app sends the DEL byte (0x7f) for the Backspace key, which the React TUI's Ink library maps to forward-delete rather than backspace. This causes backspace to appear as a space character instead of deleting text.

Solution

Document the workaround: use iTerm2 (which sends the correct backspace sequence), and reference the existing fix in the main branch.

Testing

• Verified backspace works correctly after fix on macOS
• Tested with MiniMax M2.7-highspeed model

Related

• Issue: [Bug]: Backspace key not working in macOS Terminal.app #234

[tjb-tech]

Thanks for the docs PR. I reviewed it against the current main branch. Since the TUI has already been fixed to handle Terminal.app's raw DEL byte (0x7f), I did not merge the original wording as-is because it could make users think iTerm2 is still the required workaround.

Instead, I updated README on main in commit d248975 with a troubleshooting note that says:

• current OpenHarness handles both common Backspace/delete sequences;
• users seeing the issue should upgrade first;
• terminal remapping / alternate terminals are only temporary workarounds for older versions.

CI is green. This should cover the same user-facing problem with less stale guidance.