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/errors.ts

@@ -0,0 +1,46 @@
+export interface ErrorBody {
+  error: {
+    code: string;
+    message: string;
+    fields?: Record<string, string>;
+    key_id?: number;
+  };
+}
+
+export function errorBody(
+  code: string,
+  message: string,
+  extra?: { fields?: Record<string, string>; key_id?: number },
+): ErrorBody {
+  return {
+    error: {
+      code,
+      message,
+      ...(extra?.fields ? { fields: extra.fields } : {}),
+      ...(extra?.key_id !== undefined ? { key_id: extra.key_id } : {}),
+    },
+  };
+}
+
+export const ERR = {
+  invalid_credentials: () =>
+    errorBody("invalid_credentials", "用户名或密码错误"),
+  session_expired: () =>
+    errorBody("session_expired", "会话已过期，请重新登录"),
+  already_initialized: () =>
+    errorBody("already_initialized", "系统已初始化，无法重复引导"),
+  key_already_registered: (key_id: number) =>
+    errorBody("key_already_registered", "这枚 key 已经登记过", { key_id }),
+  member_name_taken: () =>
+    errorBody("member_name_taken", "成员名称已被占用"),
+  upstream_unreachable: () =>
+    errorBody("upstream_unreachable", "上游站点暂时不可达，请稍后重试"),
+  not_found: () => errorBody("not_found", "请求的资源不存在"),
+  bad_request: () => errorBody("bad_request", "请求格式错误"),
+  validation_failed: (fields: Record<string, string>) =>
+    errorBody("validation_failed", "请检查表单填写", { fields }),
+  internal: () =>
+    errorBody("internal", "服务暂时不可用，请稍后重试"),
+  too_many_requests: () =>
+    errorBody("too_many_requests", "操作过于频繁，请稍后再试"),
+} as const;