Implement FIN-WP-0006-T01 settlement statement join; mark FIN-WP-0004/0005 blocked

Add SettlementStatement schema and a dedicated settlement_statements store
(ingest_settlement_statement, current_settlement_statements) so
resource-control internal transfer settlements join as a referenced
projection without ever entering the booked-cost ledger. exchange_health
now surfaces a current statement with payment_recognition=unknown as a
settlement_awaiting_payment_join residual instead of booked cost. Adds
CLI commands finhub ledger ingest-settlement / settlements.

FIN-WP-0006-T01 is done; the workplan is finished.

Reviewed all other open workplans for closeable work: FIN-WP-0004's only
remaining task (T05) waits on an external provider fact from
resource-control, and every FIN-WP-0005 task waits on operator/Steuerbüro
confirmation or a non-production DATEV tenant. Neither has actionable
in-repo work right now, so both move to status: blocked.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 242919@bnt-lap001
Assistant-Session: 286d235a-1654-40ff-b8fd-eee4e2ff9ea6

tests/fixtures/settlement-statement-2026-08.json

@@ -0,0 +1,28 @@
+{
+  "schema_version": "0.1",
+  "record_type": "settlement_statement",
+  "terms_version": "V0.1",
+  "financial_entity_id": "entity:frontier",
+  "procuring_entity_id": "entity:railiance",
+  "period": "2026-08",
+  "statement_date": "2026-09-01",
+  "due_date": "2026-09-15",
+  "currency": "EUR",
+  "line_items": [
+    {"resource_id": "resource:platform:audit-storage", "delivered_cost_eur": "42.10", "markup_eur": "6.32"}
+  ],
+  "known_delivered_cost_eur": "42.10",
+  "known_transfer_price_eur": "48.42",
+  "unknown_cost_remainder": false,
+  "prior_outstanding_eur": "0.00",
+  "recognized_payments_eur": null,
+  "payment_recognition": "unknown",
+  "interest_eur": "0.00",
+  "new_transfer_charges_eur": "48.42",
+  "outstanding_eur": "48.42",
+  "credit_limit_eur": "500.00",
+  "credit_headroom_eur": "451.58",
+  "consumption_mode": "open",
+  "next_month_allowance_eur": null,
+  "payment_instruction": null
+}