fix(template): show issuer name in Bill From; ignore empty string fields; nudge invoice number 2pt down

- vienna: drop `show-name: false` on the issuer party-block so the recipient sees the issuer name in Bill From (the hero already shows it, but customers expect it duplicated in the address block on paper invoices).
- components: `has()` was treating "" the same as a real value, leaving a blank line whenever a field was cleared via the CLI's empty-string update path. Reject empty strings alongside `none`.
- vienna: bump the `№ <number>` baseline by +2pt (visually ~2px) so the number sits a touch lower under the title bar instead of crowding the rule.

Author: longevityboris

typst/shared/components.typ

@@ -79,7 +79,7 @@
 #let party-block(party, theme, label-text: "To", show-name: true) = {
   let mute = th(theme, "mute", rgb("#666"))
   let display = th(theme, "display-font", ("Helvetica Neue", "Helvetica", "Arial", "New Computer Modern"))
-  let has(k) = k in party and party.at(k) != none
+  let has(k) = k in party and party.at(k) != none and party.at(k) != ""
   lbl(theme, label-text)
   v(sp.s)
   if show-name {

typst/templates/vienna.typ

@@ -78,7 +78,7 @@
   ],
 )
 
-#v(-2mm)
+#v(-2mm + 2pt)
 #align(right)[
   #fit-size(
     (9pt, 8.5pt, 8pt),
@@ -100,7 +100,7 @@
   columns: (1fr, 1fr),
   column-gutter: 14mm,
   party-block(d.client, theme, label-text: "Bill to"),
-  party-block(d.issuer, theme, label-text: "Bill from", show-name: false),
+  party-block(d.issuer, theme, label-text: "Bill from"),
 )
 
 #v(mm-sp.s)