refactor: migrate Markdown to AsciiDoc

CODE_OF_CONDUCT.adoc

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+== Contributor Covenant Code of Conduct
+
+=== Our Pledge
+
+We pledge to make participation a harassment-free experience for
+everyone.
+
+=== Our Standards
+
+*Positive behavior:* * Using welcoming language * Being respectful of
+differing viewpoints * Accepting constructive criticism * Focusing on
+what is best for the community
+
+*Unacceptable behavior:* * Harassment, trolling, or personal attacks *
+Publishing private information without permission
+
+=== Enforcement
+
+Report issues to the maintainers. All complaints will be reviewed.
+
+=== Attribution
+
+Adapted from https://www.contributor-covenant.org/[Contributor Covenant]
+v2.1.

CONTRIBUTING.adoc

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+== Contributing
+
+Thank you for your interest in contributing! We follow a "`Dual-Track`"
+architecture where human-readable documentation lives in the root and
+machine-readable policies live in `+.machine_readable/+`.
+
+=== How to Contribute
+
+We welcome contributions in many forms:
+
+* *Code:* Improving the core stack or extensions
+* *Documentation:* Enhancing docs or AI manifests
+* *Testing:* Adding property-based tests or formal proofs
+* *Bug reports:* Filing clear, reproducible issues
+
+=== Getting Started
+
+[arabic]
+. *Read the AI Manifest:* Start with `+0-AI-MANIFEST.a2ml+` (if present)
+to understand the repository structure.
+. *Environment:* Use `+guix develop+` or `+direnv allow+` to set up your
+tools.
+. *Task Runner:* Use `+just+` to see available commands
+(`+just --list+`).
+
+=== Development Workflow
+
+==== Branch Naming
+
+....
+docs/short-description       # Documentation
+test/what-added              # Test additions
+feat/short-description       # New features
+fix/issue-number-description # Bug fixes
+refactor/what-changed        # Code improvements
+security/what-fixed          # Security fixes
+....
+
+==== Commit Messages
+
+We follow https://www.conventionalcommits.org/[Conventional Commits]:
+
+....
+<type>(<scope>): <description>
+
+[optional body]
+
+[optional footer]
+....
+
+Types: `+feat+`, `+fix+`, `+docs+`, `+test+`, `+refactor+`, `+ci+`,
+`+chore+`, `+security+`
+
+=== Reporting Bugs
+
+Before reporting: 1. Search existing issues 2. Check if it’s already
+fixed in `+main+`
+
+When reporting, include: - Clear, descriptive title - Environment
+details (OS, versions, toolchain) - Steps to reproduce - Expected vs
+actual behaviour
+
+=== Code of Conduct
+
+All contributors are expected to adhere to our
+link:CODE_OF_CONDUCT.md[Code of Conduct].
+
+=== License
+
+By contributing, you agree that your contributions will be licensed
+under the same license as the project (see LICENSE).