fix: SPDX headers (AGPL→PMPL), email, author name

- AGPL-3.0-or-later → PMPL-1.0-or-later in SPDX-License-Identifier lines
- jonathan.jewell@open.ac.uk → j.d.a.jewell@open.ac.uk
- "hyperpolymath" → "Jonathan D.A. Jewell" in author fields

Part of global TODO cleanup (2026-03-16).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

README.adoc

@@ -96,7 +96,7 @@ PMPL-1.0-or-later (Palimpsest License)
 
 == Authors
 
-Jonathan D.A. Jewell <jonathan.jewell@open.ac.uk>
+Jonathan D.A. Jewell <j.d.a.jewell@open.ac.uk>
 
 == Acknowledgments