Flesh out dd0c/alert: webhook routes, incident API, notification config, data layer

- Webhook routes: Datadog, PagerDuty, OpsGenie, Grafana with per-tenant HMAC/token auth
- Incident API: list (filtered), detail with alerts, acknowledge/resolve/suppress, dashboard summary
- Notification config: CRUD with upsert, test endpoint, Slack/email/webhook channels
- Grafana normalizer: severity mapping (critical/warning/info)
- Data layer: withTenant() RLS wrapper, Zod config validation
- Fastify server entry point with cors/helmet

products/03-alert-intelligence/src/config/index.ts

@@ -0,0 +1,13 @@
+import { z } from 'zod';
+
+const envSchema = z.object({
+  PORT: z.coerce.number().default(3000),
+  DATABASE_URL: z.string().default('postgresql://localhost:5432/dd0c_alert'),
+  REDIS_URL: z.string().default('redis://localhost:6379'),
+  JWT_SECRET: z.string().min(32).default('dev-secret-change-me-in-production!!'),
+  CORS_ORIGIN: z.string().default('*'),
+  LOG_LEVEL: z.string().default('info'),
+});
+
+export const config = envSchema.parse(process.env);
+export type Config = z.infer<typeof envSchema>;