docs(xce-test-cli-ux): commit requirements/design/tasks spec-phase artifacts

Captures the spec-authoring work from earlier in this session: expanded
requirements.md (Requirements 8-13 added during discussion: detailed
help content, destructive-command confirmation, actionable flag
suggestions, bug-1711/bug-1557 fixes, and the source command), plus
the corresponding spec.json phase/approval updates. design.md and
tasks.md were already committed alongside the first implementation
task (0748f10c); this closes the gap so the full spec-authoring
history is captured in version control, matching the approvals the
user already gave interactively during this session's requirements
review, design review, and task-plan generation.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019jaMf9QEwpugH2W9KAuc7f

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

@@ -1,22 +1,22 @@
 {
   "feature_name": "xce-test-cli-ux",
   "created_at": "2026-08-26T08:38:15Z",
-  "updated_at": "2026-08-26T09:44:21Z",
+  "updated_at": "2026-09-08T22:15:00Z",
   "language": "en",
-  "phase": "requirements-generated",
+  "phase": "tasks-generated",
   "approvals": {
     "requirements": {
       "generated": true,
-      "approved": false
+      "approved": true
     },
     "design": {
-      "generated": false,
-      "approved": false
+      "generated": true,
+      "approved": true
     },
     "tasks": {
-      "generated": false,
-      "approved": false
+      "generated": true,
+      "approved": true
     }
   },
-  "ready_for_implementation": false
+  "ready_for_implementation": true
 }