docs(contributing): retire mandatory DCO sign-off

[masarray]

Owner-directed contribution policy update

At the repository owner's explicit request in this ARSAS maintenance conversation, stop requiring DCO Signed-off-by trailers for future commits and remove the repeated manual-amend bottleneck. This is an intentional, visible change to project policy, not a fabricated contributor sign-off or an undocumented bypass.

Exact scope

Only three governance files:

• CONTRIBUTING.md: remove per-commit DCO sign-off rule and example; explicitly state the existing DCO.txt and historical trailers are retained as historical records, not an active gate.
• docs/LICENSING.md: synchronize contribution policy.
• .github/pull_request_template.md: replace DCO checkbox with an affirmative CLA/rights acknowledgement.

Retain CLA, GPL and commercial-license wording, accurate Git author identity, source/third-party provenance review, independent-implementation policy, CI and IEC 61850 operational safety. Do not change the CLA's substantive terms or historical commits.

No-regression boundary

Base is the freshly merged two-file formatter PR #417 at 40355bca78341f02ecdc2c10199a1df062570897. No application, engine, tests, discovery, reporting, release, tag, engine pin, build, or runtime file changes. No new physical IED acceptance is claimed.

Validation

Diff is exactly 3 policy/template files, 1 commit, and no Signed-off-by trailer is claimed. Full PR CI and post-merge main checks will be used as the engineering gate. Any repository action that still enforces DCO must be identified and removed explicitly rather than silently disabled. Tracks #380.

Integration result

• Owner-directed policy change merged into main via GitHub rebase as 7ef6cadaaa15fb47dc234fe9519bbdb0163a8036.
• Verified the merged tree and exactly three files; CONTRIBUTING.md, docs/LICENSING.md, and the PR template all state the new contribution requirements. No DCO trailer was added to the policy commit.
• Pre-merge Build ARSAS succeeded with 1,319 application tests and no failures. Both post-merge main workflows succeeded on exact SHA 7ef6cadaaa15fb47dc234fe9519bbdb0163a8036: Build ARSAS (1,319 app tests; portable EXE publish and smoke test) and Smart Discovery Post-Merge Production Verification (988 engine + 1,319 app tests; zero failures).
• Existing historical sign-offs remain; future DCO sign-off is not a project merge requirement. CLA and provenance/security/engineering requirements remain unchanged.

[masarray]

Policy-gate audit for owner-directed removal of mandatory DCO trailers:

• Repository code search for exact Signed-off-by, DCO.txt and DCO sign-off identified the active requirement in CONTRIBUTING.md, docs/LICENSING.md and .github/pull_request_template.md; this three-file PR updates all three. No DCO-enforcing GitHub rulesets are configured. The original DCO.txt and historical commit metadata are not rewritten or discarded.
• Contribution rights/provenance remain explicitly covered by affirmative CLA agreement, accurate Git authorship, third-party/license review and independent implementation policy. No waiver of GPL, commercial licensing, CI or safety controls.
• refactor(formatting): avoid second legacy scalar extraction #417 is already merged on main at 40355bca78341f02ecdc2c10199a1df062570897 with 2/2 post-merge CI success, 1,319 app and 988 engine tests green. This PR only changes policy docs/template, not runtime.
• Transitional governance choice: the repository owner's explicit instruction is to retire the DCO requirement; this policy-change commit intentionally does not contain an impersonated owner sign-off. Do not retroactively claim a contributor certification. The project owner directs the policy change, while the existing CLA text itself remains intact.

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 8a0d3377a1

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Use a working CLA URL in generated PR bodies

When this template is used to create a pull request, the Markdown is rendered at /masarray/arsas/pull/<number>, where ../CONTRIBUTOR-LICENSE-AGREEMENT.md resolves to /masarray/arsas/CONTRIBUTOR-LICENSE-AGREEMENT.md rather than the repository file under /blob/<branch>/. The agreement checkbox therefore sends contributors to a missing page precisely when they need to review the now-required CLA; use a repository-root URL containing /blob/main/ (or a full permanent URL) instead. This matters because the repository explicitly makes the PR template part of its validation workflow.

AGENTS.md reference: AGENTS.md:L227-L227

Useful? React with 👍 / 👎.