docs(kiro): reconcile spec metadata, promote 3 new specs, fix template path

- config-upgrade-snapshot, raft-adapter-conformance: correct stale
  phase metadata (both showed "tasks-generated" though every task was
  already complete) and record their validate-impl GO decisions with
  known-limitations notes (bug-1471/bug-1472-remainder, bug-1474
  angle-b) for future spec ownership.
- component-failover-adoption: catch up design/requirements/research
  docs to the Phase 6 fix (bug-1548/bug-1549, commit d479b707) that
  landed after this spec was already marked closed.
- Promote 3 roadmap backlog items to specs (2026-08-10 discovery):
  component-rejoin-resync (apiserver/scheduler rejoin resync),
  worker-rejoin-resync (worker job-fact resync, hard prereq for
  raft-apply-decoupling's facts half), scheduler-sim-diagnostics
  (open-ended scheduler REPL debug/troubleshoot capability).
- roadmap.md updated to reflect all of the above.
- kiro-steering/kiro-steering-custom SKILL.md: fix stale template path
  (templates/steering/ -> .kiro/settings/templates/steering/) plus
  minor doc corrections in the other kiro-spec-* skills.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.kiro/specs/component-rejoin-resync/spec.json

@@ -0,0 +1,24 @@
+{
+  "feature_name": "component-rejoin-resync",
+  "created_at": "2026-08-10T00:00:00Z",
+  "updated_at": "2026-08-10T00:00:00Z",
+  "language": "en",
+  "phase": "brief",
+  "description": "apiserver and scheduler reconnect/rejoin resync efficiency -- full-state resend today; investigate whether a measured cost problem justifies delta/session-token re-attach. Sibling of worker-rejoin-resync (disjoint data: list-state vs job-execution facts).",
+  "approvals": {
+    "requirements": {
+      "generated": false,
+      "approved": false
+    },
+    "design": {
+      "generated": false,
+      "approved": false
+    },
+    "tasks": {
+      "generated": false,
+      "approved": false
+    }
+  },
+  "ready_for_implementation": false,
+  "blocked_on": []
+}