uploading a OpenPGP public key with many signatures leads to HTTP error 413 request entity too large

when uploading a public key with a lot of signatures the JavaScript request fails with HTTP status code 413.

Please allow larger uploads or suggest to use a minified public key instead of the full key:

```
gpg --export -a --export-options export-minimal
```

I could successfully upload the minified public key.

The issue names no source file or test. Start by tracing the JavaScript public-key upload request and the request-size handling; done means a full key with many signatures no longer produces HTTP 413, or the minified-key guidance is clearly provided.

Written by the indexing model from the issue text.