Adapt economics dashboard to sole-member zero-cost reality

Update membership, revenue, and cost registries to one active member with
no running costs. Refresh dashboard report and tests for €8.99 revenue and
100% gross margin.

projects/coulomb-pricing/data/revenue.json

@@ -2,15 +2,15 @@
   "version": 1,
   "entries": [
     {
-      "id": "rev-2026-06-estimate",
+      "id": "rev-2026-06-founder",
       "period": "2026-06",
-      "gross_amount": "80.91",
-      "fees_amount": "2.46",
+      "gross_amount": "8.99",
+      "fees_amount": "0.00",
       "refunds_amount": "0.00",
-      "net_amount": "78.45",
+      "net_amount": "8.99",
       "currency": "EUR",
-      "source": "manual_estimate",
-      "note": "Seed estimate for Sprint 1; replaced by Stripe sync in Sprint 3"
+      "source": "manual",
+      "note": "Single-member subscription; Stripe sync in Sprint 3"
     }
   ]
 }