chore(licence): normalise to MPL-2.0 + CC-BY-SA-4.0 (canonical pair) (#30)

Estate licence normalisation. LICENSES/={MPL-2.0,CC-BY-SA-4.0}; root
LICENSE=verbatim MPL-2.0 (GitHub display); code->MPL-2.0,
docs(.md/.adoc)->CC-BY-SA-4.0; vendored untouched. Residual mentions
(mostly legitimate anti-AGPL rules): 13. Manual-review licence PR.

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

Author: hyperpolymath

.gitattributes

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-License-Identifier: MPL-2.0
 # RSR-compliant .gitattributes
 
 * text=auto eol=lf

.github/workflows/workflow-linter.yml

@@ -36,7 +36,7 @@ jobs:
             fi
           done
           if [ $failed -eq 1 ]; then
-            echo "Add '# SPDX-License-Identifier: PMPL-1.0' as first line"
+            echo "Add '# SPDX-License-Identifier: MPL-2.0' as first line"
             exit 1
           fi
           echo "All workflows have SPDX headers"

.gitignore

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-License-Identifier: MPL-2.0
 # RSR-compliant .gitignore
 
 # OS & Editor

CHANGELOG.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MPL-2.0
+// SPDX-License-Identifier: CC-BY-SA-4.0
 = Changelog
 
 All notable changes to this project will be documented in this file.

CHANGELOG.md

@@ -1,5 +1,5 @@
 <!--
-SPDX-License-Identifier: MPL-2.0
+SPDX-License-Identifier: CC-BY-SA-4.0
 SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell (hyperpolymath)
 -->
 

CONTRIBUTING.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MPL-2.0
+// SPDX-License-Identifier: CC-BY-SA-4.0
 = Contributing Guide
 
 == Getting Started