Flesh out dd0c/cost: ingestion with Welford optimistic locking, anomaly API, governance, baselines

- Ingestion API: batch cost events, Welford baseline update with optimistic locking (version column), anomaly detection inline
- Anomaly API: list (filtered), acknowledge, snooze (1-168h), mark expected, dashboard summary with hourly trend
- Governance API: mode status, promotion eligibility check with FP rate calculation
- Baseline API: list with computed stddev, reset per resource
- Data layer: withTenant() RLS wrapper, Zod config with ANOMALY_THRESHOLD
- Fastify server entry point

products/05-aws-cost-anomaly/src/index.ts

@@ -0,0 +1,29 @@
+import Fastify from 'fastify';
+import cors from '@fastify/cors';
+import pino from 'pino';
+import { config } from './config/index.js';
+import { registerAnomalyRoutes } from './api/anomalies.js';
+import { registerBaselineRoutes } from './api/baselines.js';
+import { registerGovernanceRoutes } from './api/governance.js';
+import { registerIngestionRoutes } from './api/ingestion.js';
+
+const logger = pino({ name: 'dd0c-cost', level: config.LOG_LEVEL });
+
+const app = Fastify({ logger: true });
+
+await app.register(cors, { origin: config.CORS_ORIGIN });
+
+app.get('/health', async () => ({ status: 'ok', service: 'dd0c-cost' }));
+
+registerIngestionRoutes(app);
+registerAnomalyRoutes(app);
+registerBaselineRoutes(app);
+registerGovernanceRoutes(app);
+
+try {
+  await app.listen({ port: config.PORT, host: '0.0.0.0' });
+  logger.info({ port: config.PORT }, 'dd0c/cost started');
+} catch (err) {
+  logger.fatal(err, 'Failed to start');
+  process.exit(1);
+}