Clarify source staging and refresh model

docs/next-steps.md

@@ -26,10 +26,14 @@ AtoCore now has:
 3. Continue controlled project ingestion only where the current corpus is still
    thin
    - a few additional anchor docs per active project
-4. Define backup and export procedures for Dalidou
+4. Define a cleaner source refresh model
+   - make the difference between source truth, staged inputs, and machine store
+     explicit
+   - move toward a project source registry and refresh workflow
+5. Define backup and export procedures for Dalidou
    - SQLite snapshot/backup strategy
    - Chroma backup or rebuild policy
-5. Keep deeper automatic runtime integration deferred until the read-only model
+6. Keep deeper automatic runtime integration deferred until the read-only model
    has proven value
 
 ## Trusted State Status