Support stubbing with a direct to-source reroute

[iwoplaza]

Describe the feature

Hi! 👋
As I noted in [Discussion 57], creating a stub that bypasses straight to source would solve ingestion through web bundlers like Vite. A similar issue (#433) already exists, but the current solution proposes using mkdist. From my experiments with it, it still requires a watch->rebuild cycle, which a stub to-source bypass would not.

Additional information

• Would you be willing to help implement this feature?