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/core/src/index.ts

@@ -0,0 +1,10 @@
+export * from "./types.ts";
+export * from "./errors.ts";
+export * from "./time.ts";
+export * from "./money.ts";
+export * from "./crypto.ts";
+export * from "./dedupe.ts";
+export * from "./schemas.ts";
+export * from "./log.ts";
+export * from "./usage.ts";
+export * from "./upstream.ts";