chore(specs): mark four finished specs implemented

scheduler-sim-diagnostics, scheduler-sim-live-allocation, xce-test-cli-ux
and eliminate-frontend-makefile had every sub-task checked but their
parent boxes and spec.json phase still read tasks-generated.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.kiro/specs/xce-test-cli-ux/spec.json

@@ -1,9 +1,9 @@
 {
   "feature_name": "xce-test-cli-ux",
   "created_at": "2026-08-26T08:38:15Z",
-  "updated_at": "2026-09-08T22:15:00Z",
+  "updated_at": "2026-09-29T12:59:52Z",
   "language": "en",
-  "phase": "tasks-generated",
+  "phase": "implemented",
   "approvals": {
     "requirements": {
       "generated": true,