Implement fin-hub T24-T26: ingest, runway, coupling, RaaS packaging

Add CSV importers, runway calculator, budget alerts, cross-hub coupling
emitters, finhub CLI, and raas-mvp-packaging docs with full test coverage.

tests/test_coupling.py

@@ -0,0 +1,24 @@
+import pytest
+
+from fin_hub.coupling.ops_hub import ServiceCostLine, build_service_cost_report
+from fin_hub.ingest.hosteurope import parse_hosteurope_csv
+from pathlib import Path
+
+
+def test_build_service_cost_report_groups_by_service():
+    rows = parse_hosteurope_csv(Path(__file__).parent / "fixtures" / "hosteurope.csv")
+    lines = [
+        ServiceCostLine(
+            service_id=row.service_id,
+            environment=row.environment,
+            period_month=row.period_month,
+            amount=row.amount,
+            currency=row.currency,
+            source=row.source,
+        )
+        for row in rows
+    ]
+    report = build_service_cost_report(lines)
+    assert report["signal"] == "service_cost_attribution"
+    assert len(report["services"]) == 2
+    assert report["totals_by_month"]["2026-06"] == pytest.approx(99.8)