Expose chunk plan provenance and safe diagnostics

internal/modules/dnd/chunk/scenes/chunker.go

@@ -51,6 +51,10 @@ func (c *Chunker) Key() string {
 	return Key
 }
 
+func (*Chunker) ExecutionClass() contracts.ExecutionClass {
+	return contracts.ExecutionClassLLMBacked
+}
+
 func (c *Chunker) ReferenceSlots() []contracts.ReferenceSlot {
 	return shared.ReferenceSlots(referenceSlotDescriptions)
 }