Migrate ckprompt to the vanity module path

docs/internal/overview.md

@@ -6,10 +6,9 @@ own the optional ConfigKit and PromptKit integrations. The
 [architecture policy](../policy/architecture.md) owns normative boundaries;
 this page inventories the implemented owners.
 
-The core and ckconfig modules declare `go.maximumdirect.net/commandkit` and
-`go.maximumdirect.net/ckconfig`. Ckprompt retains the old module and import
-identities until its planned matched release; Go treats those identities as
-distinct.
+The core, ckconfig, and ckprompt modules declare
+`go.maximumdirect.net/commandkit`, `go.maximumdirect.net/ckconfig`, and
+`go.maximumdirect.net/ckprompt`, respectively.
 
 ## Root `commandkit`