chore: merge origin/main; regenerate REGISTRY.a2ml (repairs inherited drift)

origin/main (6df21b1, PR #452) edited files under spec homes without
regenerating the derived registry, leaving main itself failing
`build-registry.sh --check` (standards#381/#399 — drift blocks every PR).
The PR merge-check inherited that drift. Merging main into this branch and
regenerating brings the registry back in sync with the combined tree
(a2ml + k9-svc source hashes). Wave 1 adds hook auto-install + a CI
remediation hint so this stops recurring.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0114ps6mY5jAH4SzbGxeuYjc

Author: claude

.machine_readable/REGISTRY.a2ml

@@ -36,7 +36,7 @@ name = "A2ML — Attested Markup Language"
 stream = "foundation"
 home = "a2ml/"
 canonical_doc = "a2ml/README.adoc"
-source_hash = "sha256:27768075cf2287320778f35f0e11666ff32e69d28cc2ae6cd5f21051f9dc4630"
+source_hash = "sha256:9ed18e704be7f0f8f991edf9dcced013691e8b62c8d7cd5a27a3d7a91c0f27dd"
 route = "the typed/verified machine-readable document format"
 
 [[spec]]
@@ -45,7 +45,7 @@ name = "K9 Self-Validating Components"
 stream = "foundation"
 home = "k9-svc/"
 canonical_doc = "k9-svc/README.adoc"
-source_hash = "sha256:2fa2fe6394de60ac7da8672dcfeb21aa65919a7df83e8cf9ee9b82b2260ab0a8"
+source_hash = "sha256:cf2afa97e93597731bdb18f8c56beba3fd553c77e19c02ad9515a919cc4bec00"
 route = "self-validating components with embedded contracts + deploy logic"
 
 [[spec]]