docs(18): create gap-closure plan 18-08 (Stripe payment_failed is non-terminal)

.planning/STATE.md

@@ -3,16 +3,16 @@ msd_state_version: "1.0"
 milestone: v1.0
 current_phase: 18
 current_phase_name: Payment Gateway
-status: verifying
+status: executing
 stopped_at: Completed 18-07-PLAN.md
-last_updated: "2026-10-13T15:47:20.826Z"
+last_updated: "2026-10-13T16:43:35.617Z"
 last_activity: 2026-10-13
 last_activity_desc: Phase 18 execution started
-state_head: 8d33af4f22338285248b483a88176b35bbe4e5b5
+state_head: 96f094bcb0b837928f7794eeac671ac402a71070
 progress:
   total_phases: 40
   completed_phases: 14
-  total_plans: 175
+  total_plans: 176
   completed_plans: 175
 gsd_state_version: "1.0"
 milestone_name: milestone
@@ -29,9 +29,9 @@ See: .planning/PROJECT.md (updated 2026-10-12)
 
 ## Current Position
 
-Phase: 18 (Payment Gateway) — EXECUTING
+Phase: 18 (Payment Gateway) — READY TO EXECUTE
 Plan: 7 of 7
-Status: Phase complete — ready for verification
+Status: Ready to execute
 Last activity: 2026-10-13 — Phase 18 execution started
 
 Progress: [████░░░░░░] 44%