feat: join audit-storage usage without inventing a booked Scaleway fact

Ingest resource-control's August technical usage, omit nulls, and
reconcile forecast + usage + booked facts. Commissioning month reports
missing_booked_fact instead of 0.00. T05 still waits on the first invoice.

tests/fixtures/platform-audit-storage-usage-2026-08.json

@@ -0,0 +1,33 @@
+{
+  "schema_version": "0.2",
+  "record_type": "usage_observation",
+  "workload": "rapp-postgres/platform-pg",
+  "cost_attribution_key": "platform:audit-storage",
+  "provider_id": "scaleway-standard-multi-az",
+  "created_at": "2026-08-14T18:24:00Z",
+  "scenario": "observed",
+  "forecast_ref": "data/forecasts/platform-audit-storage-scaleway-base-2026-08.json",
+  "rows": [
+    {
+      "period": "2026-08",
+      "database_gb": 0.6365,
+      "stored_gb": 0.0066,
+      "wal_gb": null,
+      "restore_egress_gb": null,
+      "write_requests": null,
+      "read_requests": null,
+      "infrastructure_eur": null,
+      "internal_labor_hours": null,
+      "internal_labor_eur": null,
+      "total_eur": null,
+      "backup_success_pct": 100,
+      "restore_rto_minutes": 1.08,
+      "measurement_gaps": [
+        "infrastructure_eur: no invoice for a resource commissioned 2026-08-14 (owner: fin-hub, FIN-WP-0004)"
+      ]
+    }
+  ],
+  "evidence": [
+    "resource-control:data/actuals/2026-08.json"
+  ]
+}