docs: add Codex org workflow rails

[haasonsaas]

Summary

• expand the org PR template with scope, evidence, cross-repo/release impact, and agent/automation notes
• add issue forms for cross-repo contract changes, CI/release failures, and Codex-discovered follow-ups
• add AGENTS.md plus a reusable codex-rails-check workflow for AGENTS, repo skills, and issue-template validation

Test plan

• ruby YAML parse across .github/ISSUE_TEMPLATE/.yml and .github/workflows/.yml
• actionlint .github/workflows/codex-rails-check.yml

Related Issues

• Helps #8 by giving agent-assisted PRs an explicit attribution/evidence checkbox

[cursor]

PR Summary

Low Risk
Low risk: changes are limited to GitHub issue/PR templates and a lightweight CI workflow that validates template/metadata formatting and optionally enforces AGENTS.md presence.

Overview
Updates the org default PR and issue intake experience to capture better triage/verification data. The PR template is expanded with scope checkboxes, richer test/evidence prompts, cross-repo/release impact fields, and agent/automation attribution.

Adds new issue forms for CI / Release Failure, Codex Follow-Up, and Cross-Repo Contract Change, and extends existing bug/feature templates with optional evidence/impact and acceptance/cross-repo impact sections.

Introduces AGENTS.md with repository operating rails, plus a reusable codex-rails-check workflow that validates issue template YAML, checks AGENTS.md presence/non-empty (optionally required), and enforces basic frontmatter rules for .agents/skills/**/SKILL.md.

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