fix(#1498): regenerate capability-registry.cjs in npm version lifecycle hook (#1499)

* fix(#1498): regenerate capability-registry.cjs in npm version lifecycle hook

The version npm lifecycle script now runs gen-capability-registry.cjs --write
after sync-manifest-versions.cjs stamps all capability/*.json version fields.
Without this, every npm version X.Y.Z call left capability-registry.cjs stale
(capability JSONs got the new version string, but the registry still embedded
the old ones), causing gen-capability-registry.cjs --check to fail in the RC
test suite.

- package.json version script: add gen-capability-registry --write + git add
- tests/issue-844-manifest-version-sync.test.cjs: regression guard (describe F)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: backfill changeset pr: 1499

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

.changeset/patient-tunas-jump.md

@@ -0,0 +1,7 @@
+---
+type: Fixed
+pr: 1499
+---
+**`npm version` no longer leaves `capability-registry.cjs` stale** — the `version` npm lifecycle script now regenerates and stages the capability registry after stamping new version strings into all capability manifests, preventing the 1.6.0-rc regression where `gen-capability-registry.cjs --check` failed. (#1498)
+
+<!-- docs-exempt: internal release-tooling fix; no user-facing command or API change -->