Finish the D&D audit fixes

internal/modules/dnd/shared/prompt_inputs.go

@@ -50,7 +50,16 @@ func ReferencePromptInput(slot contracts.ResolvedReferenceSlot) []byte {
 		if items[i].Digest != items[j].Digest {
 			return items[i].Digest < items[j].Digest
 		}
-		return string(items[i].Content) < string(items[j].Content)
+		if comparison := bytes.Compare(items[i].Content, items[j].Content); comparison != 0 {
+			return comparison < 0
+		}
+		if items[i].Origin.Type != items[j].Origin.Type {
+			return items[i].Origin.Type < items[j].Origin.Type
+		}
+		if items[i].MediaType != items[j].MediaType {
+			return items[i].MediaType < items[j].MediaType
+		}
+		return items[i].SizeBytes < items[j].SizeBytes
 	})
 	if len(items) == 1 {
 		return append([]byte(nil), items[0].Content...)