feat: replace revision counters with domain state contracts

Use content digests, key fingerprints, binding and trust identities, immutable mutation receipts, and observation tokens instead of state-update ordinals across API, storage, Runtime, and Web contracts.

Preserve historical replay and secret material through frozen migrations; preflight uncertain removals before cutover, resume provisioning receipts, validate encrypted migration candidates, and align fresh/upgraded schemas. Include reviewed regression fixes, generated artifacts, and validation evidence.

web/workspace/test/merge-request-status.test.ts

@@ -40,7 +40,7 @@ function reviewRequested(
     event_id: eventId,
     sequence: 1,
     subject_ref: subjectRef,
-    ticket_item_revision: "ticket-revision",
+    ticket_content_digest: "ticket-digest",
     ticket_merge_request_subjects: [
       { merge_request_id: "MR-1", subject_ref: subjectRef },
     ],
@@ -61,7 +61,7 @@ function review(
     sequence: 1,
     request_event_id: requestEventId,
     subject_ref: subjectRef,
-    ticket_item_revision: "ticket-revision",
+    ticket_content_digest: "ticket-digest",
     ticket_merge_request_subjects: [
       { merge_request_id: "MR-1", subject_ref: subjectRef },
     ],