Scaffold dd0c/cost: Welford baseline, anomaly scorer, governance engine, tests

- Welford online algorithm for running mean/stddev baselines
- Anomaly scorer: z-score → 0-100 mapping, property-based tests (10K runs, fast-check)
- Governance engine: 14-day auto-promotion with FP rate gate, injectable Clock
- Panic mode: defaults to active (safe) when Redis unreachable
- Tests: 12 scorer cases (incl 2x 10K property-based), 9 governance cases, 3 panic mode cases
- PostgreSQL schema with RLS: baselines (optimistic locking), anomalies, remediation_actions
- Fly.io config, Dockerfile

products/05-aws-cost-anomaly/package.json

@@ -0,0 +1,39 @@
+{
+  "name": "dd0c-cost",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "tsx watch src/index.ts",
+    "build": "tsc",
+    "start": "node dist/index.js",
+    "test": "vitest run",
+    "lint": "eslint src/ tests/"
+  },
+  "dependencies": {
+    "fastify": "^4.28.0",
+    "@fastify/cors": "^9.0.0",
+    "pg": "^8.12.0",
+    "ioredis": "^5.4.0",
+    "zod": "^3.23.0",
+    "jsonwebtoken": "^9.0.2",
+    "pino": "^9.1.0",
+    "uuid": "^9.0.1",
+    "@aws-sdk/client-cost-explorer": "^3.600.0",
+    "@aws-sdk/client-cloudtrail": "^3.600.0",
+    "@aws-sdk/client-dynamodb": "^3.600.0",
+    "@aws-sdk/lib-dynamodb": "^3.600.0",
+    "@slack/web-api": "^7.1.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.5.0",
+    "tsx": "^4.15.0",
+    "vitest": "^1.6.0",
+    "fast-check": "^3.19.0",
+    "@types/node": "^20.14.0",
+    "@types/pg": "^8.11.0",
+    "@types/jsonwebtoken": "^9.0.6",
+    "@types/uuid": "^9.0.8",
+    "eslint": "^9.5.0"
+  }
+}