Cleaned up the code a bit (thx gpt4), with:
- dynamic module load: JS is chunked up and deferred to PDF loading,
which improves all the sessions where PDFs are not loaded
- unified path for drag/drop and 'load file' (shall call it "magic drop"
so PDFs are text'ified upon drag/dop as well
- fixed "not being able to load the same doc twice" (thx gpt4)
- using minified worker, as it's loaded dynamically, we save ~50% bandwidth