docs: declare MPL-2.0 + CC-BY-SA-4.0 standard licence; de-drift CLAUDE.md (#56)

* docs(licensing): declare MPL-2.0 + CC-BY-SA-4.0 as the standard licence

Make the dual-licence standard explicit and authoritative for both humans and
machines, mirroring the estate LICENCE-POLICY.adoc:

- LICENSING.adoc (root): the standard — MPL-2.0 for code/config/scripts/build/
  metadata/specs, CC-BY-SA-4.0 for prose docs (the two SPDX lines in normal use,
  one per file by class). Documents that the root LICENSE carries MPL-2.0 as the
  single licence GitHub detects (the community-health / "git health" marker),
  the file-class mapping, and the exclusion cases (third-party flag-not-edit;
  platform-registry MPL-2.0; 007/son-shared/PMPL not applicable to this repo).
- .machine_readable/licensing-policy.toml: machine-readable twin (tools enforce
  from the TOML; the .adoc is the source of truth).
- README: point the licensing section at LICENSING.adoc and note the MPL-2.0
  GitHub marker.
- root-allow.txt: admit LICENSING.adoc as an authority file.

Honestly flagged for owner decision (NOT swept — per the no-bulk-SPDX /
neurophone#99 guardrail): 5 Apache-2.0 proof files under academic/formal-
verification (Lean/Coq/Agda ecosystem convention vs MPL-2.0 default) and 2
PMPL-1.0 workflow files (.github/workflows/{scorecard,secret-scanner}.yml —
drift, since Phronesis is not a Palimpsest carve-out repo).

Root LICENSE (MPL-2.0) and LICENSES/{MPL-2.0,CC-BY-SA-4.0}.txt already correct.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AqMopxUsgu78rg5fhWBUkk

* docs(claude): de-drift .claude/CLAUDE.md to the canonical estate policy

Resolve the Hypatia structural-drift (SD007) finding on .claude/CLAUDE.md by
re-syncing it to the canonical hyperpolymath/standards .claude/CLAUDE.md. This
pulls in the full current estate policy that the prior divergent copy was
missing: the five-way License Policy (highest-priority guardrail), the complete
language table (Rust/SPARK, Zig, Idris2, Agda, Gleam, Elixir, …), the V-lang /
ATS2 / ReScript / Python bans, the Mustfile/justfile build system, and the
TypeScript / ReScript / npm / JavaScript exemption tables.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AqMopxUsgu78rg5fhWBUkk

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

Author: hyperpolymath