feat(core,db): 业务核心与数据访问层

core：DTO/错误信封/时间口径/微分折算/dedupe_key/加密与 PBKDF2/契约 zod/logtape/上游客户端。
db：八表 Drizzle schema + 仓储 + drizzle 配置。

packages/db/package.json

@@ -0,0 +1,22 @@
+{
+  "name": "@new-api-key-usage/db",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "exports": {
+    ".": "./src/index.ts"
+  },
+  "scripts": {
+    "db:generate": "drizzle-kit generate",
+    "db:push": "drizzle-kit push",
+    "db:studio": "drizzle-kit studio"
+  },
+  "dependencies": {
+    "drizzle-orm": "^0.45.3",
+    "postgres": "^3.4.9"
+  },
+  "devDependencies": {
+    "@types/pg": "^8.23.1",
+    "drizzle-kit": "^0.31.11"
+  }
+}