docs(stovepipe): align record RFC with the shipped stage and hook framework

The record stage landed in #555 while this doc still read as a proposal,
so the RFC described a design rather than the code. Re-frames it as-built
and corrects the contract details that drifted: ValidationFact carries no
Queue field (the queue is the store binding and the leading PK column),
Get takes (uri, project), the Record payload carries queue_name beside the
request id, degrees are the named DegreeGreen/DegreeBroken constants,
LastGreenRequestID is shipped rather than proposed, and the bookmark's CAS
conflict is absorbed by the retry loop rather than returned. Adds the two
algorithm steps the doc omitted (deserialize, per-queue storage resolution)
and the ordering rationale for advancing the bookmark only after the fact
is durable.

Replaces the inline Hooks design with integration against hook-framework.md,
which supersedes it: a HookEvent published to a per-domain hook topic and
dispatched to a pluggable extension, not a Notify() call out of the stage.
Records where the publish belongs, the event shape, and the decision that
`type` names the scope (validation.repository.recorded) rather than the
outcome, since scope is the axis consumers cannot route on later.

Documents that record_dlq has no consumer even though dead-lettering is
enabled on the subscription, so rejected messages accumulate unread.

Author: mnoah1

doc/rfc/index.md

@@ -28,7 +28,7 @@ Design documents and technical proposals, grouped by scope. Shared/cross-cutting
 - [Process stage](stovepipe/steps/process.md) - Build-strategy decision, per-queue concurrency gate, backlog coalescing, entity model, platform prerequisites
 - [Build stage](stovepipe/steps/build.md) - Trigger-only stage and Stovepipe's URI-based BuildRunner contract
 - [Buildsignal stage](stovepipe/steps/buildsignal.md) - Build polling, terminal status persistence, and the handoff to record
-- [Record stage](stovepipe/steps/record.md) - Immutable validation facts, Queue coordination, Hooks notification, and the Phase 1 handoff to analyze
+- [Record stage](stovepipe/steps/record.md) - Immutable validation facts keyed by `(queue, uri, project)`, monotonic last-green bookmark advancement, and the deferred hook-event and analyze handoffs
 
 ## Runway