chore(licence): normalise to MPL-2.0 + CC-BY-SA-4.0 (canonical pair) (#48)

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): 295. Manual-review licence PR.

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

Author: hyperpolymath

.github/workflows/codeql.yml

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: PMPL-1.0
+# SPDX-License-Identifier: MPL-2.0
 name: CodeQL Security Analysis
 
 on:

.github/workflows/scorecard.yml

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: PMPL-1.0
+# SPDX-License-Identifier: MPL-2.0
 name: Scorecards supply-chain security
 
 on:

.github/workflows/secret-scanner.yml

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: PMPL-1.0
+# SPDX-License-Identifier: MPL-2.0
 name: Secret Scanner
 
 on:

.machine_readable/agent_instructions/README.adoc

@@ -1,5 +1,3 @@
-SPDX-License-Identifier: MPL-2.0
-
 Mozilla Public License Version 2.0
 ==================================