docs(18-01): complete household timezone accessor + IANA validator plan

.planning/STATE.md

@@ -4,13 +4,13 @@ milestone: v1.1
 milestone_name: Operability & Polish
 status: executing
 stopped_at: Phase 18 context gathered
-last_updated: "2026-06-15T01:53:38.101Z"
-last_activity: 2026-06-15 -- Phase 18 planning complete
+last_updated: "2026-06-15T02:08:26.245Z"
+last_activity: 2026-06-15
 progress:
   total_phases: 23
   completed_phases: 9
-  total_plans: 32
-  completed_plans: 32
+  total_plans: 36
+  completed_plans: 33
   percent: 39
 ---
 
@@ -21,14 +21,14 @@ progress:
 See: .planning/PROJECT.md (updated 2026-06-10)
 
 **Core value:** One color-coded family calendar (shared + personal) and shared lists from a single low-friction PWA — cross-ecosystem, no app store
-**Current focus:** Phase 11 — per-event-reminders
+**Current focus:** Phase 18 — auto-timezone-detection-and-ability-to-change-timezone
 
 ## Current Position
 
-Phase: 13
-Plan: Not started
+Phase: 18 (auto-timezone-detection-and-ability-to-change-timezone) — EXECUTING
+Plan: 2 of 4
 Status: Ready to execute
-Last activity: 2026-06-15 -- Phase 18 planning complete
+Last activity: 2026-06-15
 
 ### ✅ Resolved Checkpoint — Phase 15 Plan 15-03 Task 2 (human-action)
 
@@ -107,6 +107,7 @@ _Updated after each plan completion_
 | Phase 10-admin-role-settings P03 | 720 | 3 tasks | 6 files |
 | Phase 10-admin-role-settings P04 | 1315 | 3 tasks | 8 files |
 | Phase 11-per-event-reminders P11-04 | 60 | 3 tasks | 4 files |
+| Phase 18-auto-timezone-detection-and-ability-to-change-timezone P01 | 2 | 2 tasks | 2 files |
 
 ## Accumulated Context
 
@@ -252,9 +253,9 @@ Recent decisions affecting current work:
 
 ## Session Continuity
 
-Last session: 2026-06-15T01:25:46.029Z
+Last session: 2026-06-15T02:08:26.229Z
 Stopped at: Phase 18 context gathered
-Resume file: .planning/phases/18-auto-timezone-detection-and-ability-to-change-timezone/18-CONTEXT.md
+Resume file: None
 
 ## Operator Next Steps