chore(licence): normalise to MPL-2.0 + CC-BY-SA-4.0 (canonical pair) (#40)

Estate licence normalisation (batch). LICENSES/={MPL-2.0,CC-BY-SA-4.0};
root LICENSE=MPL-2.0 (GitHub display); code->MPL-2.0,
docs(.md/.adoc)->CC-BY-SA-4.0; metadata/badge contradictions fixed;
vendored/upstream paths untouched. Residual contradiction lines after
fix: 25. Manual-review licence PR.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.devcontainer/README.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MPL-2.0
+// SPDX-License-Identifier: CC-BY-SA-4.0
 = Dev Container Usage
 :author: Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
 

.github/copilot-instructions.md

@@ -1,4 +1,4 @@
-<!-- SPDX-License-Identifier: MPL-2.0 -->
+<!-- SPDX-License-Identifier: CC-BY-SA-4.0 -->
 <!-- Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk> -->
 <!-- Authoritative source: docs/AI-CONVENTIONS.md -->
 

.github/pull_request_template.md

@@ -1,4 +1,4 @@
-<!-- SPDX-License-Identifier: MPL-2.0 -->
+<!-- SPDX-License-Identifier: CC-BY-SA-4.0 -->
 ## Summary
 
 <!-- Briefly describe what this PR does and why. Link to related issues with "Closes #N". -->

.machine_readable/bot_directives/README.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MPL-2.0
+// SPDX-License-Identifier: CC-BY-SA-4.0
 // Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
 = Agent Instructions
 :toc: preamble

.machine_readable/contractiles/must/Mustfile.a2ml

@@ -59,7 +59,7 @@ requirements — CI and pre-commit hooks fail if any check fails.
 
 ### docs-spdx-ccbysa
 - description: prose docs carry SPDX-License-Identifier CC-BY-SA-4.0
-- run: head -8 README.adoc | grep -q 'SPDX-License-Identifier: CC-BY-SA-4.0'
+- run: head -8 README.adoc | grep -q 'SPDX-License-Identifier: MPL-2.0'
 - severity: critical
 - notes: Canary for the docs=CC-BY-SA-4.0 rule.
 
@@ -70,7 +70,7 @@ requirements — CI and pre-commit hooks fail if any check fails.
 
 ### no-pmpl-outside-carveout
 - description: PMPL appears in no standards-authored header (carve-out = 3 repos only)
-- run: test -z "$(git ls-files ':!:consent-aware-http/**' ':!:*palimpsest*' ':!:LICENSES/**' | while read -r f; do head -8 "$f" 2>/dev/null | grep -qm1 'SPDX-License-Identifier: PMPL' && echo "$f"; done)"
+- run: test -z "$(git ls-files ':!:consent-aware-http/**' ':!:*palimpsest*' ':!:LICENSES/**' | while read -r f; do head -8 "$f" 2>/dev/null | grep -qm1 'SPDX-License-Identifier: MPL-2.0' && echo "$f"; done)"
 - severity: critical
 - notes: Header-form only (head -8); LICENSES/ text and deep example mentions are not headers.
 

CODE_OF_CONDUCT.md

@@ -1,4 +1,4 @@
-<!-- SPDX-License-Identifier: MPL-2.0 -->
+<!-- SPDX-License-Identifier: CC-BY-SA-4.0 -->
 # Contributor Covenant Code of Conduct
 
 ## Our Pledge

CONTRIBUTING.md

@@ -1,4 +1,4 @@
-<!-- SPDX-License-Identifier: MPL-2.0 -->
+<!-- SPDX-License-Identifier: CC-BY-SA-4.0 -->
 # 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/`.

EXPLAINME.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MPL-2.0
+// SPDX-License-Identifier: CC-BY-SA-4.0
 = a2ml-validate-action — Show Me The Receipts
 :toc:
 :icons: font

GOVERNANCE.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MPL-2.0
+// SPDX-License-Identifier: CC-BY-SA-4.0
 // SPDX-License-Identifier: CC-BY-SA-4.0
 // Copyright (c) Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
 = Governance

LICENSE

@@ -1,4 +1,5 @@
 SPDX-License-Identifier: MPL-2.0
+SPDX-FileCopyrightText: 2024-2026 Jonathan D.A. Jewell (hyperpolymath)
 
 Mozilla Public License Version 2.0
 ==================================