FRE-4471: Scaffold DarkWatch MVP — monorepo, schema, services, API routes, tests

- Turborepo monorepo structure (packages: api, db, types, jobs; services: darkwatch)
- Prisma schema: User, WatchListItem, Exposure, Alert, ScanJob models
- WatchListService: CRUD with normalization, dedup, tier-based limits
- HIBPService: API integration with severity scoring
- MatchingEngine: exact-match with content hash dedup
- AlertPipeline: dedup window, email notifications
- ScanService: orchestrates watch list -> HIBP -> match -> alert flow
- BullMQ job workers for scan and alert processing
- Fastify API routes: watchlist, exposures, alerts, scan
- Docker Compose: PostgreSQL 16 + Redis 7
- 15 unit tests passing
- Implementation plan document uploaded

turbo.json

@@ -0,0 +1,26 @@
+{
+  "$schema": "https://turbo.build/schema.json",
+  "tasks": {
+    "build": {
+      "dependsOn": ["^build"],
+      "outputs": ["dist/**"]
+    },
+    "dev": {
+      "cache": false,
+      "persistent": true
+    },
+    "test": {
+      "dependsOn": ["build"],
+      "inputs": ["src/**/*.ts", "test/**/*.ts"]
+    },
+    "lint": {
+      "inputs": ["src/**/*.ts"]
+    },
+    "db:migrate": {
+      "cache": false
+    },
+    "db:seed": {
+      "cache": false
+    }
+  }
+}