Add explicit pipeline configuration imports

docs/internal/overview.md

@@ -28,7 +28,7 @@ progress and artifact services resolve durable inputs and outputs.
 | --- | --- | --- |
 | Executable | `cmd/narratio` | Process entry, standard stream wiring, argument handoff, and exit status. |
 | Application orchestration | `internal/app` | Command dispatch, configuration selection, secret-file environment loading, production composition, session locking, planning, execution, restore, cleanup gates, and user-facing reporting. |
-| Configuration | `internal/config` | Strict YAML loading, discovery, defaults, normalization, session templating, and validation. |
+| Configuration | [`internal/config`](configuration.md) | Presence-aware pipeline composition, strict YAML loading, discovery, defaults, normalization, session templating, and validation. |
 | Pipeline stages | `internal/stage` | Canonical stage registry, shared stage contract, execution dependencies, and implemented stage behavior. |
 | External boundaries | `internal/adapters`, `internal/audio` | WhisperX HTTP, downstream subprocesses, notification, object storage, and S3 audio materialization behind Narratio contracts. |
 | Manifests | `internal/manifest` | Durable session progress, invocation audit state, stage transitions, validation, and atomic persistence. |
@@ -82,6 +82,8 @@ trimmed transcript state: neither invalidates the other, while either can stale
 
 ## Focused Documentation
 
+- [Configuration Internals](configuration.md): pipeline composition, import
+  confinement, field ownership, decoding, and root-relative path semantics.
 - [Adapter Internals](adapters.md): external adapter boundaries, composition,
   failure behavior, and test surfaces.
 - [Artifact Internals](artifacts.md): source identities, runtime catalog,