Use translation keys for all FX row labels; append currency dynamically

All four FX sub-row labels now come from config translations instead of
hardcoded English strings. Labels with a currency suffix (per-item,
total-foreign) have the currency code appended by updateFxLabels() so
they read e.g. "Price per item in USD" / "Line total in USD" and update
when the foreign currency dropdown changes. Language switching also
re-applies all four labels via the existing updateFxLabels() call in
relabel().

Translation key values updated:
- currency-code  → "Foreign currency code"
- exchange-rate  → "Exchange rate" (dropped the redundant convention note)
- per-item       → "Price per item in"  (currency appended at runtime)
- total-foreign  → "Line total in"      (currency appended at runtime)

PDF note updated to match: "Price per item in USD: 100.00 (35 THB per USD)"

https://claude.ai/code/session_0151QtsUhzXmgzEhSvXG2SDt

app/config.yml

@@ -408,25 +408,25 @@ translations:
     fr: Devise étrangère
     "no": Utenlandsk valuta
   currency-code:
-    en: Currency code
+    en: Foreign currency code
-    de: Währungscode
+    de: Fremdwährungscode
-    fr: Code devise
+    fr: Code devise étrangère
-    "no": Valutakode
+    "no": Utenlandsk valutakode
   exchange-rate:
-    en: "Exchange rate (1 foreign = X local)"
+    en: Exchange rate
-    de: "Wechselkurs (1 Fremd = X Inland)"
+    de: Wechselkurs
-    fr: "Taux de change (1 étranger = X local)"
+    fr: Taux de change
-    "no": "Valutakurs (1 utenlandsk = X lokal)"
+    "no": Valutakurs
   per-item:
-    en: Price per item (foreign currency)
+    en: Price per item in
-    de: Preis je Einheit (Fremdwährung)
+    de: Preis je Einheit in
-    fr: Prix par unité (devise étrangère)
+    fr: Prix par unité en
-    "no": Pris per enhet (utenlandsk valuta)
+    "no": Pris per enhet i
   total-foreign:
-    en: Line total in foreign currency
+    en: Line total in
-    de: Zeilenbetrag (Fremdwährung)
+    de: Zeilenbetrag in
-    fr: Total ligne en devise étrangère
+    fr: Total ligne en
-    "no": Linjebeløp i utenlandsk valuta
+    "no": Linjebeløp i
   add-line:
     en: "+ Add new line"
     de: "+ Neue Zeile hinzufügen"

app/index.html

@@ -931,11 +931,11 @@ function toggleFx(i) {
     <td colspan="6">
       <div class="fx-grid">
         <div>
-          <div class="fx-label">${t("currency-code")}</div>
+          <div class="fx-label" id="fcur-lbl-${i}">${t("currency-code")}</div>
           <select id="fcur-${i}" onchange="updateFxLabels(${i});calcLine(${i});saveLines()">${currOpts(defaultFcy)}</select>
         </div>
         <div>
-          <div class="fx-label">Exchange rate</div>
+          <div class="fx-label" id="frate-lbl-${i}">${t("exchange-rate")}</div>
           <div style="display:flex;align-items:center;gap:4px;flex-wrap:wrap">
             <input type="number" id="frate-${i}" value="" min="0" step="any" style="width:80px" oninput="calcFxFromPer(${i})">
             <select id="rcur-${i}" style="width:auto" onchange="updateFxLabels(${i});calcFxFromPer(${i});saveLines()">
@@ -947,11 +947,11 @@ function toggleFx(i) {
           </div>
         </div>
         <div>
-          <div class="fx-label" id="fper-lbl-${i}">Price per item in ${h(defaultFcy)}</div>
+          <div class="fx-label" id="fper-lbl-${i}">${t("per-item")} ${h(defaultFcy)}</div>
           <input type="number" id="fper-${i}" value="" min="0" step="any" oninput="calcFxFromPer(${i})">
         </div>
       </div>
-      <div class="fx-note">${t("total-foreign")}: <strong id="fltot-${i}">0.00</strong></div>
+      <div class="fx-note"><span id="ftot-lbl-${i}">${t("total-foreign")} ${h(defaultFcy)}</span>: <strong id="fltot-${i}">0.00</strong></div>
     </td>`;
   lr?.insertAdjacentElement("afterend", fxTr);
   calcLine(i);
@@ -1406,7 +1406,7 @@ function buildPDF() {
     let   fxH     = 0;
     if (row.fxNote) {
       const fxOther = row.fxNote.rcur === iCur ? row.fxNote.cur : iCur;
-      const fxStr = `${td("per-item")}: ${row.fxNote.cur} ${fmt(row.fxNote.per)} `
+      const fxStr = `${td("per-item")} ${row.fxNote.cur}: ${fmt(row.fxNote.per)} `
                   + `(${(+row.fxNote.rate).toFixed(5)} ${row.fxNote.rcur} per ${fxOther})`;
       const fxLines = sp(fxStr, CD + CP - 4);
       fxH = fxLines.length * 3.5 + 1;
@@ -1440,7 +1440,7 @@ function buildPDF() {
 
     if (row.fxNote) {
       const fxOther = row.fxNote.rcur === iCur ? row.fxNote.cur : iCur;
-      const fxStr = `${td("per-item")}: ${row.fxNote.cur} ${fmt(row.fxNote.per)} `
+      const fxStr = `${td("per-item")} ${row.fxNote.cur}: ${fmt(row.fxNote.per)} `
                   + `(${(+row.fxNote.rate).toFixed(5)} ${row.fxNote.rcur} per ${fxOther})`;
       fn(7); tc(107,114,128);
       const fxLines = sp(fxStr, CD + CP - 4);
@@ -1491,14 +1491,20 @@ function updateFxLabels(i) {
   const lcy      = document.getElementById("icur")?.value || "";
   const rcurEl   = document.getElementById(`rcur-${i}`);
   const rotherEl = document.getElementById(`rother-${i}`);
-  const pl       = document.getElementById(`fper-lbl-${i}`);
   if (rcurEl) {
     const prev = rcurEl.value;
     rcurEl.innerHTML = `<option value="${h(lcy)}">${h(lcy)}</option><option value="${h(fcy)}">${h(fcy)}</option>`;
     rcurEl.value = (prev === lcy || prev === fcy) ? prev : lcy;
   }
   if (rotherEl) rotherEl.textContent = rcurEl?.value === lcy ? fcy : lcy;
-  if (pl) pl.textContent = `Price per item in ${fcy}`;
+  const cl = document.getElementById(`fcur-lbl-${i}`);
+  if (cl) cl.textContent = t("currency-code");
+  const rl = document.getElementById(`frate-lbl-${i}`);
+  if (rl) rl.textContent = t("exchange-rate");
+  const pl = document.getElementById(`fper-lbl-${i}`);
+  if (pl) pl.textContent = t("per-item") + " " + fcy;
+  const tl = document.getElementById(`ftot-lbl-${i}`);
+  if (tl) tl.textContent = t("total-foreign") + " " + fcy;
 }
 
 // ── Save / load invoice lines ──────────────────────────────────────────────────