build(prompts-core): bundle markdown prompt variants

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/markdown-modules.d.ts

@@ -0,0 +1,4 @@
+declare module "*.md" {
+  const content: string
+  export default content
+}