chore(release): v0.4.0, since LINKS-OPEN-REFS is a new check

Same precedent as v0.2.0 and v0.3.0: a new check code is a minor bump,
not a patch. Bundles the register row for repo #20, the schemaless-host
fix, the reference dedup and the new OK/SKIP outcomes on checkLinks.

Also records the register-freshness decision in CLAUDE.md: --refresh
runs HERE before every release, and consumers of the register are told
not to check freshness themselves. Twice running a newly published repo
was missing when a census ran, and the cost landed in a DIFFERENT repo
than the stale one — portfolio-optimiser's status line stayed put
through a round in which it fixed everything really wrong with it.
Two owners of one invariant is the drift this register exists to remove.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NxP9N3p1fG6UYSB8rATBL6

package.json

@@ -1,6 +1,6 @@
 {
   "name": "repo-standard",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "private": true,
   "type": "module",
   "engines": {