Log the provider docs split in the changelog

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,25 @@
 # Changelog
 
+## 2026-09-16 11:46 UTC — Provider blueprint split into contract, spec template and appendix
+
+- **`docs/provider-contract.md`** is the generic provider specification: MUST/SHOULD/MAY
+  rules with the caller behind each one, 19 behaviour-profile axes with stable codes
+  (where providers may differ, such as blocking vs submit-and-return Create, or a
+  backend with no provisioning state), error taxonomy, credential hygiene, testing
+  obligations, the adding-a-provider checklist and the contract's known limits. It
+  names no existing provider.
+- **`docs/provider-spec-template.md`** is the fill-in questionnaire a new provider's
+  design answers before implementation; entry numbers match the contract's profile
+  table.
+- **`docs/providers-existing.md`** maps kubernetes, gcp and kvm to every profile and
+  keeps their per-provider reference notes, shared gaps and proposed features.
+- **`docs/providers.md`** is now an index; README, CLAUDE.md and architecture.md point
+  at the new files. This supersedes the single-file blueprint written earlier on the
+  same branch.
+- Two rules the callers enforce that were not written down before: orphan GC sweeps
+  providers sequentially with no deadline, so a hung `ListByTag` stalls all collection;
+  and the reconciler deletes an instance a backend reports as Stopped before start.
+
 ## 2026-09-16 08:45 UTC — Provider health checks: ProviderHealth CRD, per-provider checks, gauges
 
 - **Each configured provider is now checked on a schedule** and reported in a