refactor(root): relocate the contributing guide into .github/ (#155)

refactor(root): relocate the contributing guide into .github/

The estate canonical location is .github/CONTRIBUTING.md, which GitHub
auto-discovers; the root copy is removed and references are updated in
the same
change.

  * .github/CONTRIBUTING.md
      (new)
  * 0-AI-MANIFEST.a2ml
  * CONTRIBUTING.adoc
      (deleted)
  * MAINTAINERS.adoc
  * docs/wiki/Contributing.md
  * docs/wiki/README.md

Author: hyperpolymath

.github/CONTRIBUTING.md

@@ -0,0 +1,28 @@
+<!--
+SPDX-License-Identifier: CC-BY-SA-4.0
+Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
+-->
+
+# Contributing Guide
+
+## Getting Started
+
+1.  Fork the repository
+
+2.  Create a feature branch from `main`
+
+3.  Sign off commits (`git` `commit` `-s`)
+
+4.  Submit a pull request
+
+## Commit Guidelines
+
+- Conventional commits: `type(scope):` `description`
+
+- Sign all commits (DCO required)
+
+- Atomic, focused commits
+
+## License
+
+Contributions licensed under project license.

0-AI-MANIFEST.a2ml

@@ -21,7 +21,7 @@ purpose = """
 root-context  = "docs/CLAUDE.adoc"
 project-state = ".machine_readable/descriptiles/STATE.a2ml"
 roadmap       = "ROADMAP.adoc"
-contributing  = "CONTRIBUTING.adoc"
+contributing  = ".github/CONTRIBUTING.md"
 audit-trail   = "AUDIT.adoc"
 rsr-status    = "RSR_COMPLIANCE.adoc"
 

CONTRIBUTING.adoc

@@ -62,4 +62,4 @@ For questions about project governance:
 
 * link:GOVERNANCE.adoc[Governance Model]
 * link:CODE_OF_CONDUCT.md[Code of Conduct]
-* link:CONTRIBUTING.adoc[Contributing Guide]
+* link:.github/CONTRIBUTING.md[Contributing Guide]

MAINTAINERS.adoc

@@ -4,7 +4,7 @@ Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
 -->
 # Contributing
 
-Short summary; the authoritative version is [`CONTRIBUTING.adoc`](../../CONTRIBUTING.adoc) at the root.
+Short summary; the authoritative version is [`../../.github/CONTRIBUTING.md`](../../.github/CONTRIBUTING.md) at the root.
 
 ## Language policy (hard rule)
 

docs/wiki/Contributing.md

@@ -49,7 +49,7 @@ that runs the above on every push to main. Tracked in
 | `Verification.md` | Build + CI matrix |
 | `ABI.md` | Idris2 ABI + DivMod lemma surface |
 | `Roadmap.md` | Short; cross-links to ROADMAP.adoc |
-| `Contributing.md` | Short; cross-links to CONTRIBUTING.adoc |
+| `Contributing.md` | Short; cross-links to ../../.github/CONTRIBUTING.md |
 | `Glossary.md` | CNO, =st=, postulate, etc. |
 | `FAQ.md` | Common questions |
 | `Audit-Trail.md` | Resolved + open audit items |