repo: add Bugbot review instructions and reset copilot md

[martinsander00]

Resolves: https://github.com/malbeclabs/infra/issues/2387

Summary

• This pull request adds a Bugbot instruction file at the repository root so Cursor writes pull request comments in Simplified Technical English.
• It also resets copilot-instructions.md file
• Each finding must use the headings Issue, Context, and Proposed Fix.

Testing

• Open this pull request and wait for the Cursor Bugbot check.
• If the check does not start, comment cursor review on this pull request.
• Confirm a finding uses the three headings and reads in Simplified Technical English.

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Note

Low Risk
Only AI review prompt files and a changelog line change; no application or onchain behavior.

Overview
Adds .cursor/BUGBOT.md so Cursor Bugbot reviews use Simplified Technical English and a fixed Issue / Context / Proposed Fix layout for each finding. CHANGELOG records this as an experimental CI/review change.

Replaces the long DoubleZero-specific content in .github/copilot-instructions.md with the same short STE template, so repo-wide GitHub Copilot review guidance no longer carries the prior architecture overview, review posture, or universal defect rules (path-scoped .github/instructions/* files are unchanged by this diff).

^{Reviewed by Cursor Bugbot for commit d62f69d. Bugbot is set up for automated code reviews on this repo. Configure here.}

[martinsander00]

cursor review

[cursor]

Skipping Bugbot: Unable to authenticate your request. Please make sure Bugbot is properly installed and configured for this repository.

[martinsander00]

cursor review

[cursor]

✅ Bugbot reviewed your changes and found no new issues!

Comment @cursor review or bugbot run to trigger another review on this PR

^{Reviewed by Cursor Bugbot for commit cf827ef. Configure here.}