Add integration and artifact contract documentation

docs/internal/modules.md

@@ -78,8 +78,8 @@ Artifact type and schema version:
 - schema version: `v1`
 
 The extractor adds prompt and response-schema provenance to lane manifest
-metadata. Durable artifact payload details belong in the D&D spell artifact
-integration doc.
+metadata. Durable artifact payload details belong in the
+[D&D spell artifact contract](../integrations/dnd-spell-artifacts.md).
 
 ## D&D Spell Validators
 
@@ -139,8 +139,9 @@ Provides:
 
 - `encoded`
 
-Durable output file shapes belong in the JSON output integration doc. Operator
-behavior belongs in [Operations](../operations.md).
+Durable output file shapes belong in the
+[JSON output contract](../integrations/json-output.md). Operator behavior
+belongs in [Operations](../operations.md).
 
 ## Production Registration