I tried copy-paste from Inkscape to Libre Office, but it translates into a (blurry) bitmap image. How to copy to the clipboard as vector-drawing? Or does the translation happen in Libre Office? 

Text files normally are printer files. A printer need a raster or pixel graphic for printing. Inkscape produce draw files, line graphics or SVG-Files.

If you would like to have a draw graphic in your text file, you have to store your SVG-File from Inkscape as PDF-File. This you can open in LibreOffice draw. From here you can copied it to the place in your text file.

The other way round is also possible. When you store a text-file in PDF-File and open it in Inkscape you get a line-graphic (path → object change to path). But careful, the whole text split into lines with grouped words, all words split into there letters (but still grouped) and all letters where split into path (with fill).

Except there is a pixel-graphic in the text file. This would not changed.

BmP

Current version of Inkscape imports PDF text with words or sentences as single paths. It is necessary to Path/Split Path to separate the individual glyphs.