Auto-commit extra files (#197)

Whenever Dyad does a commit from a proposal, it will automatically amend
the commit with outside changes (e.g. made outside of Dyad).

This helps avoid a lot of user confusion, e.g.
https://github.com/dyad-sh/dyad/issues/187

https://www.reddit.com/r/dyadbuilders/comments/1kjysc0/error_pushing_images/

Edge cases:
If a user adds a file outside of Dyad, and then they hit retry, it will
revert these outside changes, but it's still technically in the version
history, so I think it's OK. This should also be a pretty unusual
situation.

Fixes #164 
Fixes #187

src/ipc/handlers/chat_stream_handlers.ts

@@ -535,7 +535,8 @@ This conversation includes one or more image attachments. When the user uploads
           event.sender.send("chat:response:end", {
             chatId: req.chatId,
             updatedFiles: status.updatedFiles ?? false,
-            uncommittedFiles: status.uncommittedFiles,
+            extraFiles: status.extraFiles,
+            extraFilesError: status.extraFilesError,
           } satisfies ChatResponseEnd);
         } else {
           event.sender.send("chat:response:end", {