Rename selected configuration profiles to overlays

docs/roadmap/deferred.md

@@ -15,7 +15,7 @@ The initial release deliberately excludes:
 
 - automatic `conf.d` discovery;
 - remote imports, arbitrary providers, and additional configuration formats;
-- custom merge strategies, sequence merging, reset operators, and profile inheritance;
+- custom merge strategies, sequence merging, reset operators, and overlay inheritance;
 - parser-specific or custom structural-decoding extension APIs;
 - generic dynamic-subtree conversion and module-registry APIs;
 - automatic schema migrations;

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Configuration Overlay Rename Implementation Plan
 
-Status: not started. Execute Stage 1, then Stage 2.
+Status: Stage 1 complete. Execute Stage 2.
 
 ## Scope and operating instructions
 
@@ -112,6 +112,15 @@ unchanged.
 Stage 1 is complete only with a compiling, passing repository and matching
 current documentation. It is not permission to ship before Stage 2's audit.
 
+### Completion
+
+Completed 2026-09-23. Renamed the selected configuration feature across the
+facade, engine, maintained consumer, fixtures, contract, and current guidance;
+application-owned `ModelProfile` and `model_profile` remain unchanged. `gofmt` and
+`./scripts/check.sh` passed on Go 1.26.8/linux. Review confirmed the new
+`overlays/<name>.yml` path, `overlay`/`overlay.*` public values, and no retained
+legacy Go declarations or filesystem fallback.
+
 ## Stage 2 — Verify the breaking migration and finalize the handoff
 
 ### Outcome

docs/roadmap/overlays.md

@@ -17,7 +17,7 @@ not authorize publication or changes to downstream repositories.
 
 The baseline is ConfigKit at `aead20f`, following v0.3.1 and the release-workflow
 simplification. Current behavior is owned by the
-[selected-profile contract](../config.md#selected-profiles). This roadmap owns
+[selected-overlay contract](../config.md#selected-overlays). This roadmap owns
 the unimplemented rename; it is not a new current API reference.
 
 ## Target terminology and public surface