docs: add Signed commits section to CONTRIBUTING

[hyperpolymath]

Adds a Signed commits section to this repo's CONTRIBUTING, per owner ruling D218. The estate policy is docs/SIGNING-POLICY.adoc in hyperpolymath/standards.

This repo's default branch is covered by the zero-bypass Require-Signed-Commits ruleset, and rebase-merge is off. The section tells contributors what that requires:

• People and interactive agents sign with an SSH signing key.
• Apps, bots and workflows write through the API, so GitHub signs their commits.
• PRs are merged with squash.

If the file already had its own signing section, that section is replaced in place instead of adding a second one. Lines elsewhere that told people to sign with GPG are changed to match the policy (SSH for people).

This is a docs-only change. The commit was created through createCommitOnBranch, so GitHub signs it.

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Reviewing files that changed from the base of the PR and between 782be61 and a3a1172.

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• .github/CONTRIBUTING.md

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🔇 Additional comments (1)

.github/CONTRIBUTING.md (1)

123-138: LGTM!

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📝 Summary

Summary by CodeRabbit

• Documentation
  • Added contribution guidance requiring commits to the default branch to be signed with a registered SSH key and verified committer email. Unsigned pushes are rejected.
  • Clarified that every commit on a pull request branch is checked, and that branches containing unsigned commits should be recreated with signed cherry-picks before opening a new pull request.
  • Documented squash-merging as the required approach; rebase-merging is disabled. Apps, bots and workflows must use the approved API or signing action to write changes.

Walkthrough

The contribution guide now sets out commit-signing requirements, instructions for automated commit creation, and pull request merge guidance.

Changes

Commit signing

Layer / File(s)	Summary
Signing and merge instructions .github/CONTRIBUTING.md	The guide requires signed commits on pull request branches, describes how to replace unsigned commits, and states that rebase-merge is disabled.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~4 minutes

Change: Other

Merge Risk: ⚪ Minimal · up to a3a11

The available evidence establishes no actionable signing or merge failure, so no material merge risk is identified.

Architecture Summary

Architecture risk: 🔵 Low · up to a3a11

The changed surface does not map to a changed system, dependency edge, entrypoint, or external dependency.

Changed systems: None identified.

Architecture concerns
No architecture-level concerns identified.

Review details

Before / after behavior

• observed — Modified behavior in .github/CONTRIBUTING.md: Added commit-signing requirements and contributor instructions for SSH signing, automated commit creation, and PR merging. The section specifies that every PR-branch commit must be signed, gives steps for replacing unsigned commits, and states that rebase-merge is disabled.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description clearly explains the purpose and main changes, but it omits the required RSR Quality Checklist and Testing sections. It also does not follow the supplied template structure.	Add the template sections for Summary, Changes, RSR Quality Checklist, Testing, and Screenshots where applicable. Complete the required checklist items and state the testing performed, or explain why testing is not applicable for this docum…

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise, specific, and accurately describes the documentation change.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Description check

Resolution

Add the template sections for Summary, Changes, RSR Quality Checklist, Testing, and Screenshots where applicable. Complete the required checklist items and state the testing performed, or explain why testing is not applicable for this documentation-only change.

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_{A rabbit checks each commit’s seal,
Then signs each hop with care and zeal.
It cherry-picks a signed new track,
And sends a squash-merge bouncing back.
The guide now shows the path to take,
For every branch the team will make.}

_{Comment @coderabbitai help to get the list of available commands.}

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

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