fix(core): #131 type error if declaration is set to true in tsconfig

Do now show type errors on defineConfig, if declaration is set to true in the tsconfig.
We export all zod types to fix the type error.
See microsoft/TypeScript#42873

.changeset/few-stingrays-bow.md

@@ -0,0 +1,5 @@
+---
+"@content-collections/core": patch
+---
+
+Do now show type errors on defineConfig, if declaration is set to true in the tsconfig.

packages/core/src/config.ts

@@ -4,6 +4,11 @@ import { Parser, Parsers } from "./parser";
 import { CacheFn } from "./cache";
 import { NotSerializableError, Serializable } from "./serializer";
 
+// Export all zod types to fix type errors,
+// if declaration is set to true in tsconfig.json.
+// @see https://github.com/microsoft/TypeScript/issues/42873
+export type * from "zod";
+
 export type Meta = {
   filePath: string;
   fileName: string;