Improve archive management

### Is your feature request related to a problem?

Confusion may arise when building the archive for the website download.
If the archive contains the archive name in the root folder, this will not correctly deploy the website on the blockchain, as aeweb will not point directly to the index.html to display the site.

### Describe the solution you'd like

Scan the location of the index.html (node access point) and validate the tree structure with the user.

### Additional context

_No response_

### Epic

_No response_

Inspect the archive-building flow and reproduce a website download whose root contains the archive name instead of index.html. Trace how the index.html location and archive tree are handled, then verify that the user is warned about an invalid structure before deployment.

Written by the indexing model from the issue text.