fix(shared): add ancestor project discovery helpers

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

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

src/shared/index.ts

@@ -67,5 +67,6 @@ export * from "./session-directory-resolver"
 export * from "./prompt-tools"
 export * from "./internal-initiator-marker"
 export * from "./plugin-command-discovery"
+export * from "./project-discovery-dirs"
 export { SessionCategoryRegistry } from "./session-category-registry"
 export * from "./plugin-identity"