feat: add durable Kuknos settlement coordination

infrastructure/postgres/migrations/000003_kuknos_settlements.up.sql

@@ -0,0 +1,22 @@
+CREATE TABLE kuknos_settlements (
+    id uuid PRIMARY KEY,
+    source_service text NOT NULL CHECK (source_service <> ''),
+    source_transaction_id text NOT NULL CHECK (source_transaction_id <> ''),
+    idempotency_key text NOT NULL UNIQUE CHECK (idempotency_key <> ''),
+    status text NOT NULL CHECK (status IN ('PENDING','SUBMITTED','CONFIRMED','RETRYABLE','MANUAL_REVIEW')),
+    network text NOT NULL DEFAULT 'kuknos',
+    signed_transaction_xdr text NOT NULL DEFAULT '',
+    transaction_hash text NOT NULL DEFAULT '',
+    attempts integer NOT NULL DEFAULT 0 CHECK (attempts >= 0),
+    available_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+    locked_at timestamptz,
+    locked_by text NOT NULL DEFAULT '',
+    last_error text NOT NULL DEFAULT '',
+    submitted_at timestamptz,
+    confirmed_at timestamptz,
+    manual_review_at timestamptz,
+    created_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+    updated_at timestamptz NOT NULL DEFAULT clock_timestamp()
+);
+
+CREATE INDEX kuknos_settlements_due_idx ON kuknos_settlements (status, available_at);

infrastructure/postgres/migrations/000004_settlement_operator_audit.up.sql

@@ -0,0 +1,13 @@
+CREATE TABLE kuknos_settlement_operator_audits (
+    id bigserial PRIMARY KEY,
+    settlement_id uuid NOT NULL REFERENCES kuknos_settlements(id),
+    actor_id text NOT NULL CHECK (actor_id <> ''),
+    action text NOT NULL CHECK (action IN ('RETRY')),
+    reason text NOT NULL CHECK (reason <> ''),
+    previous_status text NOT NULL,
+    resulting_status text NOT NULL,
+    created_at timestamptz NOT NULL DEFAULT clock_timestamp()
+);
+
+CREATE INDEX kuknos_settlement_operator_audits_settlement_idx
+    ON kuknos_settlement_operator_audits (settlement_id, created_at DESC);

infrastructure/postgres/migrations/000005_settlement_reconciliation_issues.up.sql

@@ -0,0 +1,13 @@
+CREATE TABLE kuknos_reconciliation_issues (
+    settlement_id uuid PRIMARY KEY REFERENCES kuknos_settlements(id),
+    issue_type text NOT NULL CHECK (issue_type IN ('MISSING_LEDGER_CONFIRMATION','TRANSACTION_HASH_MISMATCH')),
+    expected_hash text NOT NULL DEFAULT '',
+    actual_hash text NOT NULL DEFAULT '',
+    status text NOT NULL DEFAULT 'OPEN' CHECK (status IN ('OPEN','RESOLVED')),
+    first_detected_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+    last_detected_at timestamptz NOT NULL DEFAULT clock_timestamp(),
+    resolved_at timestamptz
+);
+
+CREATE INDEX kuknos_reconciliation_issues_open_idx
+    ON kuknos_reconciliation_issues (status, last_detected_at DESC);