- views/pages.templ: upload input now has "multiple" attribute; page
title/heading updated to plural ("Bücher hochladen"); templ regenerated
- internal/web/handlers.go: uploadSubmit now reads all files from
r.MultipartForm.File["book"] instead of a single r.FormFile, saving
each via a new saveUpload helper; partial failures are reported per
filename while successfully saved files are kept
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>