Extract core assets for clean workspace (#66)

Major refactoring to establish a clean, focused structure:

**New Structure:**
- legal/ - License texts (PMPL-1.0, MPL-2.0, exhibits, historical)
- docs/ - Consolidated documentation (GUIDE, FAQ, INTEGRATION)
- tools/ - Rust CLI tools (pmpl-sign, pmpl-verify, pmpl-audit)
- spec/ - Formal specifications (AsciiDoc)
- research/ - Curated papers and presentations

**Added:**
- PALIMPSEST-MPL-1.0.txt - New v1.0 license based on MPL-2.0
- Exhibit A - Ethical Use Guidelines
- Exhibit B - Quantum-Safe Provenance Specification
- Rust tools: pmpl-sign, pmpl-verify, pmpl-audit
- CI integrations: GitHub Actions, GitLab CI, GitLoom
- Language examples: Rust, Elixir, Ada

**Removed:**
- 40+ obsolete directories (ARCHIVE, campaigns, press-lobby-kit, etc.)
- Fragmented version directories (GUIDES_v0.4, METADATA_v0.4, etc.)
- Legacy code (Haskell, OCaml, Ruby, PHP integrations)
- Redundant configuration files (.scm, .ncl, etc.)

**Updated:**
- README.md - Clean, focused project overview
- CLAUDE.md - Updated for new structure
- CONTRIBUTING.adoc - Simplified guidelines
- Justfile - Streamlined build automation

This reduces the repository from 400+ files to ~50 essential files,
establishing clear separation: legal/docs/tools/research/spec.

Co-authored-by: Claude <noreply@anthropic.com>

Author: hyperpolymath