feat(policy): netkingdom maturity-gated publication-scope policy

Token scope is now bound to package maturity, gated on netkingdom's own maturity:
- maturity-build -> gitea-wide, maturity-test -> org-wide, maturity-prod -> repo-scoped
  (scope narrows as stakes rise; broad tokens only for low-stakes build artifacts)
- the graduated table is DORMANT until netkingdom reaches production grade; until
  then every lane clamps to repo-scope, injected as NPM_AUTH_TOKEN (fail-safe)
- token env-var name signals blast radius: NPM_AUTH_TOKEN (repo default),
  NPM_AUTH_COULOMB_TOKEN (org), NPM_AUTH_GITEA_TOKEN (gitea), NPM_AUTH_WHYNOT_TOKEN
  (npm scope, defined but unused), NPM_AUTH_WHYNOTDESIGN (explicit repo)

netkingdom is at maturity-build today, so whynot-design resolves to repo-scope /
NPM_AUTH_TOKEN. Flip netkingdom_maturity to maturity-prod to activate graduation.

- policies/netkingdom-publication-scope.yaml: the policy data + gate
- publication_policy.py: load + resolve (clamp/active, env naming, override)
- exec delivery injects under the resolved env-var name (was fixed SE_NPM_TOKEN)
- catalog lane carries delivery_config.npm.maturity
- new CLI: `secrets-engine policy publication <lane>`
- docs/publication-scope-policy.md; tests for clamp, graduation, naming, override

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/npm-publish-demo.sh

@@ -83,8 +83,11 @@ chmod +x "$WORK/npm-wrapped.sh"
 secrets-engine exec --catalog whynot-design-npm-publish -- "$WORK/npm-wrapped.sh"
 
 echo
+echo "### policy binding: which scope/token-env did the lane resolve to?"
+secrets-engine policy publication whynot-design-npm-publish | sed 's/^/    /'
+
 echo "### confirm parent shell never held the token"
-echo "    SE_NPM_TOKEN in parent: '${SE_NPM_TOKEN:-<unset>}'"
+echo "    NPM_AUTH_TOKEN in parent: '${NPM_AUTH_TOKEN:-<unset>}'"
 echo "    NPM_CONFIG_USERCONFIG in parent: '${NPM_CONFIG_USERCONFIG:-<unset>}'"
 echo
 echo "### DONE — npm publish (dry-run) ran with the token injected by secrets-engine."