Constrain nested bootstrap findings with versioned native output shapes

config/investigation.lean.toml

@@ -4,3 +4,6 @@ lean_protocol = 2
 # Temporary experiment: no periodic consolidation.
 lean_checkpoint_steps = 0
 bootstrap_json_framing = true
+
+# Versioned native object shapes for nonempty bootstrap findings.
+bootstrap_framing_version = 2