Update licensing to MPL-2.0 + Palimpsest

- LICENSE: MPL-2.0 with Palimpsest notice
- Added PALIMPSEST.adoc philosophy document
- Updated README badges
- Updated workflow SPDX headers to MPL-2.0

Legal license: MPL-2.0
Philosophical framework: Palimpsest (not yet legally binding)
Future: Palimpsest v0.5+ will integrate MPL-2.0

🤖 Generated with Claude Code

Author: Jonathan D.A. Jewell

.github/workflows/codeql.yml

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-License-Identifier: MPL-2.0
 name: CodeQL
 on:
   push:

.github/workflows/mirror.yml

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-License-Identifier: MPL-2.0
 # SPDX-FileCopyrightText: 2025 Jonathan D.A. Jewell
 name: Mirror to Git Forges
 

.github/workflows/rsr-antipattern.yml

@@ -1,4 +1,4 @@
-# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-License-Identifier: MPL-2.0
 name: RSR Language Policy
 
 on: