chore(license): PMPL → MPL-2.0 sweep (5 files) (#530)

Sole-owner repo. Per the 2026-06-02 canonical license policy, PMPL is
restricted to palimpsest-license / palimpsest-plasma /
consent-aware-http; this repo gets MPL-2.0.

Files: 5 SPDX headers flipped + NOTICE rewrite (if applicable) + orphan
PMPL license file delete (if applicable).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Signed-off-by: hyperpolymath <6759885+hyperpolymath@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

spec/ARG-PROFILE.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: PMPL-1.0-or-later
+// SPDX-License-Identifier: MPL-2.0
 // Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
 
 = ARG-PROFILE — AffineScript

spec/CRG-PROFILE.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: PMPL-1.0-or-later
+// SPDX-License-Identifier: MPL-2.0
 // Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
 
 = CRG-PROFILE — AffineScript

spec/FRG-PROFILE.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: PMPL-1.0-or-later
+// SPDX-License-Identifier: MPL-2.0
 // Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
 
 = FRG-PROFILE — AffineScript

spec/TRG-PROFILE.adoc

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: PMPL-1.0-or-later
+// SPDX-License-Identifier: MPL-2.0
 // Copyright (c) 2026 Jonathan D.A. Jewell (hyperpolymath) <j.d.a.jewell@open.ac.uk>
 
 = TRG-PROFILE — AffineScript

stdlib/future.affine

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: PMPL-1.0-or-later
+// SPDX-License-Identifier: MPL-2.0
 // SPDX-FileCopyrightText: 2025 hyperpolymath
 //
 // Future - async sequencing combinators (echidna#62)