polish(auth): Copy all non-code assets from email renderer

[dschom]

Because

• We also need to copy .css.

This pull request

• Makes the asset copy more general by simply copying all non-code files.

Issue that this pull request solves

Closes: (issue number)

Checklist

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• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).

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