Type/Client/Facture/Libellé all swap a span for an <input>/<select> via
v-if -- Vue doesn't focus a newly created element on its own, so the
first click only revealed the field and a second click was needed to
actually type into it. Added a v-focus directive (mounted() calls
el.focus() + el.select(), firing exactly once per v-if true-flip) to
all four.
Verified live: a single click on each of the four editable cells now
moves document.activeElement into the field immediately.