docs(phase-09): complete phase execution and human sign-off

All 3 UX defects fixed, 11/11 must-haves verified, human-approved.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.planning/STATE.md

@@ -5,7 +5,7 @@ milestone_name: Hardening & Validation
 current_plan: 2
 status: completed
 stopped_at: Completed 09-02-playwright-port-autofill-PLAN.md
-last_updated: "2026-04-13T15:46:11.154Z"
+last_updated: "2026-04-13T15:50:19.479Z"
 last_activity: 2026-04-13
 progress:
   total_phases: 4