chore(registry): sync git-hooks copy — spec-2.3 ordinal 53 (#96)

Why: PR #95 (spec-2.3 impl) omitted the git-hooks/spec-registry.txt
fallback-copy row that prior spec PRs carried (e.g. #93 for 2.2). The
pre-push hook prefers the sibling opendbrb registry (already updated @
opendbrb 5bb091e) so tagging was unblocked; this restores the fallback
copy's sync. Tag v0.53.0-stage2.53 already pushed dual-repo.

Spec: spec-2.3-skill-invocation.md

Co-authored-by: sqlrush <sqlrush@sqlrushdeMacBook-Pro.local>

Author: sqlrush

git-hooks/spec-registry.txt

@@ -57,3 +57,4 @@
 1.21.1	1	50	sub	tag
 2.1	2	51	main	tag
 2.2	2	52	main	tag
+2.3	2	53	main	tag