Add routes to distributions service

• Add routes /api/revenus/** and /api/previsions/** to rental-income-distributions-service (port 3005)
• Both routes reuse the existing distributionsCircuitBreaker (strict 30% failure threshold), consistent with the financial-service policy
• Updated the distributions route comment to reflect the broader scope (yield payouts, revenue KPIs, forecasts)

The rental income distributions service now exposes revenue KPI and forecast endpoints under /api/revenus and /api/previsions. Without these gateway routes, those endpoints would be unreachable from the frontend.