chore: baseline snapshot — prior-session work + ha-consistency-invariants spec family

Pre-existing uncommitted work: ha-repl-hardening payload data plane (7.x),
heartbeat liveness fix (Req 1.3), connection-reuse ASAN fixes, doc cleanup.
New: ha-consistency-invariants umbrella (requirements/design/research) and
its four implementation sub-specs (specs generated via batch, cross-spec
review applied), steering roadmap + product.md Raft+CP decision.

.kiro/specs/ha-commit-engine/spec.json

@@ -0,0 +1,23 @@
+{
+  "feature_name": "ha-commit-engine",
+  "created_at": "2026-06-11T09:07:03Z",
+  "updated_at": "2026-06-11T09:07:03Z",
+  "language": "en",
+  "phase": "tasks-generated",
+  "umbrella": "ha-consistency-invariants",
+  "approvals": {
+    "requirements": {
+      "generated": true,
+      "approved": true
+    },
+    "design": {
+      "generated": true,
+      "approved": true
+    },
+    "tasks": {
+      "generated": true,
+      "approved": true
+    }
+  },
+  "ready_for_implementation": true
+}