Enforce responsible AI contribution policy

[MikeMcQuaid]

• Keep commit history tied to accountable human contributors
• Ensure reviewers engage directly with responsible contributors

[Copilot]

Pull request overview

This PR updates Homebrew’s Responsible AI guidance and repository contribution templates, and introduces a new CI workflow to enforce commit-style rules (conventional commit prefixes and AI attribution) on pull requests.

Changes:

• Tighten documented AI/LLM contribution requirements across docs and templates (no AI commit attribution; contributors must answer questions themselves).
• Replace the previous conventional-commit-only workflow with a Commit Style workflow backed by dedicated shell scripts.
• Add a self-test script to validate the commit-style checker behavior in CI.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
docs/Responsible-AI-Usage.md	Updates Responsible AI policy and refreshes review date.
docs/How-To-Open-a-Homebrew-Pull-Request.md	Aligns contributor guidance with updated AI/LLM requirements and refreshes review date.
CONTRIBUTING.md	Aligns AI/LLM contribution requirements with updated policy.
.github/workflows/reject-conventional-commits.yml	Removes the old conventional-commit-only workflow.
.github/workflows/commit-style.yml	Adds new workflow to run commit-style scripts on PRs.
.github/scripts/check-commit-style.sh	Implements checks for conventional prefixes + AI attribution.
.github/scripts/check-commit-style-test.sh	Adds CI self-test coverage for the checker.
.github/PULL_REQUEST_TEMPLATE.md	Updates PR checklist to reflect new AI/LLM contributor requirements.
.github/ISSUE_TEMPLATE/feature.yml	Adds an AI/LLM disclosure + responder-attestation checkbox.
.github/ISSUE_TEMPLATE/bug.yml	Adds an AI/LLM disclosure + responder-attestation checkbox.

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