docs: promote raft-apply-decoupling spec family from /kiro-discovery

Adds the Raft Apply-Ordering & Hook Decoupling roadmap phase: canonical
pre-hooks -> raft commit -> apply -> notify ordering, with the raft protocol
step lifted out of the notification hook fan-out (root of the bug-795/828/
851/1060 divergence family). Decision: apply-after-commit via a single
shared apply_committed_entry() seam reused by online apply and restart
replay.

- raft-drive-async: full spec docs (brief/requirements/research/design)
  committed alongside its already-tracked tasks.md; async-drive prerequisite
  for the apply-decoupling work, sequenced to start first (threatens
  failover liveness today).
- raft-apply-decoupling: new spec (brief + facts-in-raft.md) covering the
  apply seam and the facts (WAL_MODE_RETAIN) apply-timing question (open
  decision D1).
- job-array-single-wal-record: promoted from backlog to a tracked spec,
  sequenced after raft-apply-decoupling.
- ha-consistency-invariants: add criterion 2.9 (Facts-Apply invariant),
  documenting the current on-receipt fact-reaction deviation this family
  will reconcile.
- raft-commit-safety / raft-log-replication: reconcile spec.json phase to
  "implemented" (both were mislabeled tasks-generated despite full 18/18
  and 24/24 task completion + raft_sim GO).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SDWVNQLKxqTVHh42cH7rV3

.kiro/specs/raft-log-replication/spec.json

@@ -1,9 +1,9 @@
 {
   "feature_name": "raft-log-replication",
   "created_at": "2026-06-21T11:00:00Z",
-  "updated_at": "2026-06-21T11:00:00Z",
+  "updated_at": "2026-06-25T00:00:00Z",
   "language": "en",
-  "phase": "tasks-generated",
+  "phase": "implemented",
   "approvals": {
     "requirements": {
       "generated": true,
@@ -19,5 +19,6 @@
     }
   },
   "ready_for_implementation": true,
+  "implementation_status": "implemented — library log half landed + validated (24/24 tasks, raft_sim GO per memory project_raft_log_replication_done). Phase reconciled 2026-06-25 (was mislabeled tasks-generated).",
   "note": "Auto-approved (-y mode). Extends election-only src/lib/raft into a strict raft.tla log-half implementation: ClientRequest/AppendEntries/HandleAppendEntriesRequest/HandleAppendEntriesResponse/UpdateTerm-on-any-RPC. Closes bug-851 G1/G2/G3/G5. Authoritative shared callback contract (on_persist_entry, on_get_entry_term, on_send_append_entries, on_truncate_from) consumed verbatim by raft-commit-safety, raft-sim-conformance, and ha-term-safety. Boundary: owns src/lib/raft log additions + (term,index) reconcile seam only; NOT commit-index advance, vote freshness, config, or controller WAL/transport internals."
 }