Adopt ConfigKit overlays for pipeline selection

docs/config.md

@@ -47,24 +47,24 @@ the durable copied session input.
 `narratio config validate`, `narratio config show`, `narratio config sources`,
 and `narratio config artifacts` use the same `--config`, `--campaign`,
 `--campaign-file`, and
-`--profile` selection rules as pipeline commands, but do not select, discover,
+`--overlay` selection rules as pipeline commands, but do not select, discover,
 or load a session. They resolve configured typed credential references as part
 of the ordinary ConfigKit load but expose only their environment-variable names;
 they do not create runtime state.
-`narratio config diff <left-profile> <right-profile>` uses the same pipeline and
-campaign selectors, resolves each named profile with an independent ConfigKit
-load, and does not accept a separate `--profile` flag.
+`narratio config diff <left-overlay> <right-overlay>` uses the same pipeline and
+campaign selectors, resolves each named overlay with an independent ConfigKit
+load, and does not accept a separate `--overlay` flag.
 
 Campaign selection is optional only when the resolved pipeline has no
 `scriptorium.artifact_families`. When families are declared, Narratio selects a
 campaign through an explicit flag or `pipeline.campaigns.default_campaign_id`,
 then parses the campaign-owned party and expands concrete artifacts and any
 family publish rules before validation. `config validate` prints the resulting
-root, profile, and effective digest. `config show` emits the normalized
+root, overlay, and effective digest. `config show` emits the normalized
 effective pipeline YAML, with defaults and concrete expansion included but
 ConfigKit directives and family declarations omitted. This review projection is
 not promised to be a reloadable authoring document. `config sources` prints a stable
-source projection instead of effective values: root/import/profile/default
+source projection instead of effective values: root/import/overlay/default
 ownership plus campaign/party and generated-family records. Canonical derived
 players trace to the party. `config artifacts` lists the concrete artifact map,
 effective dependencies, and defining sources. The [CLI reference](cli.md#config-validate-config-show-config-sources-config-artifacts-and-config-diff)
@@ -83,7 +83,7 @@ difference.
 Use the [production/testing bundle](../examples/production-testing/pipeline.yml)
 as the complete copyable migration reference. Keep production settings in the
 base, split them into explicit additive imports, and place testing differences
-in the fixed `profiles/testing.yml` overlay. Put ordinary artifacts and families
+in the fixed `overlays/testing.yml` overlay. Put ordinary artifacts and families
 in the recommended one-definition files shown by that bundle. Convert campaign
 rosters to [canonical party input](integrations/party.md), then express character
 work as families. Inspect the result with `config validate`, `config show`,
@@ -108,11 +108,14 @@ remote state with an unsafe legacy identity must be migrated before use.
   root-only `configkit.imports` list. Imported files contribute fields to one
   logical pipeline document; they do not override fields supplied by the root
   or another import.
-- An omitted profile, an empty profile option, and the exact name `default`
+- An omitted overlay, an empty overlay option, and the exact name `default`
   select the base configuration. Any other name selects
-  `profiles/<name>.yml` relative to the pipeline root.
+  `overlays/<name>.yml` relative to the pipeline root. Move previously selected
+  `profiles/<name>.yml` files there; the old directory is not searched, and
+  `--profile` is no longer accepted for Narratio pipeline selection. Explicit
+  imports from a directory named `profiles` remain valid.
 - Campaign, session, and canonical-party documents are strict single-source
-  ConfigKit schemas. They do not enable imports, profiles, or `configkit`
+  ConfigKit schemas. They do not enable imports, overlays, or `configkit`
   directives.
 - Configured timeout and retry-delay durations must be positive. An omitted
   artifact timeout continues to inherit its configured Scriptorium timeout.
@@ -137,10 +140,10 @@ remote state with an unsafe legacy identity must be migrated before use.
   - local (`audio_dir` or `audio_files`), or
   - S3 (`audio_s3.prefix`).
 
-### Pipeline imports and profiles
+### Pipeline imports and overlays
 
 Large pipeline configurations may be split into explicitly named fragments and
-may use fixed-path profile overlays:
+may use fixed-path selected overlays:
 
 ```yaml
 configkit:
@@ -170,12 +173,12 @@ name the full field path and every source that claimed it. Narratio additionally
 rejects an artifact or artifact-family key declared by more than one base file,
 even when those files contribute disjoint children.
 
-Profile names are case-sensitive and use ConfigKit's safe fixed-path naming
+Overlay names are case-sensitive and use ConfigKit's safe fixed-path naming
 rules. Only the selected overlay is opened; a malformed unselected overlay does
-not affect a base or different-profile load. Maps merge recursively, overlay
+not affect a base or different-overlay load. Maps merge recursively, overlay
 scalars replace base scalars, and overlay lists replace base lists completely.
 Explicit `false`, zero, empty strings, empty containers, and null values remain
-explicit inputs and are not refilled by defaults. Profiles cannot inherit,
+explicit inputs and are not refilled by defaults. Overlays cannot inherit,
 stack, import files, or declare another ConfigKit control section.
 
 During ConfigKit loading, Narratio applies fresh typed defaults, recorded
@@ -183,7 +186,7 @@ entry-level defaults and normalization, read-only file-local validation, and
 ordinary path resolution before computing a deterministic effective
 configuration digest. The digest represents the normalized, secret-free
 runtime pipeline mapping; it excludes ConfigKit directives, source
-provenance, profile identity, and raw environment secret values. Equivalent
+provenance, overlay identity, and raw environment secret values. Equivalent
 effective mappings therefore have the same digest regardless of how fields are
 split among the root and imports.
 
@@ -400,9 +403,9 @@ empty string or `default`, which explicitly select Notarius's composed base
 configuration. Notarius owns selector interpretation and validation; Narratio
 does not restrict profile names, resolve profile files, or rewrite the value.
 
-This selection is independent of Narratio's own `--profile` selection. A
+This selection is independent of Narratio's own `--overlay` selection. A
 Narratio overlay may explicitly select a differently named Notarius overlay,
-but Narratio never forwards its own profile name automatically. It is also
+but Narratio never forwards its own overlay name automatically. It is also
 independent of `pipeline.notarius.llm_api_key`: an overlay may change either or
 both fields according to the deployed Notarius configuration. See the
 [Notarius integration contract](./integrations/notarius.md) for invocation and