[REF-2535] Export don't generate the asset folder

[davibern]

Describe the bug
When the project is exported the asset folder is not generated and the images are located in the root of the directory.

To Reproduce
Steps to reproduce the behavior:
Simply create a new project, use the first template reflex creates and add an rx.image.

• Code/Link to Repo: https://github.com/davibern/Reflex-Asset-Issue/tree/main

Expected behavior
The export system create the asset folder and subfolders into assets and into them the media files the project needs.

Screenshots
When i open the index.html the console shows that errors:

Specifics (please complete the following information):

• Python Version: 3.11 and 3.12
• Reflex Version: 0.4.1 to 0.4.5
• OS: Window 11
• Browser (Optional): Edge and Chrome

_{From SyncLinear.com | REF-2535}

[davibern]

I forgot to comment that i try to include the image in rx.image with and without "/". In develop mode in localhost with both methods i can see all images, but when I export the project the asset folders doesn't exists.