inventory: hardware (keyboard-wedge) barcode scanner in Add-item

Replace the camera scanner in the Add inventory item dialog with support
for a USB barcode scanner attached to the computer. A wedge scanner types
the code as a fast keystroke burst ending in Enter; a global keydown
listener (active while the dialog is open) buffers the burst by timing and
routes it through the existing GS1 parser, so scanning a medication
auto-fills barcode/expiry/lot without focusing any field. The barcode
input also parses on Enter for manual entry. The camera BarcodeScanner
component stays (still used by patient wallet import). i18n: replace the
inventory.dialog.scan label with a scanHint across all five locales.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/lib/i18n/locales/ar/translation.json

@@ -713,7 +713,7 @@
       "expires": "تنتهي الصلاحية",
       "barcode": "الباركود / NDC",
       "barcodePlaceholder": "امسح أو اكتب رمزًا",
-      "scan": "مسح الباركود",
+      "scanHint": "وصّل ماسح باركود USB وامسح الدواء — أو اكتب الرمز.",
       "scannedTitle": "تم مسح الباركود",
       "cancel": "إلغاء",
       "submit": "إضافة عنصر",

frontend/lib/i18n/locales/de/translation.json

@@ -697,7 +697,7 @@
       "expires": "Verfällt",
       "barcode": "Barcode / NDC",
       "barcodePlaceholder": "Code scannen oder eingeben",
-      "scan": "Barcode scannen",
+      "scanHint": "Schließen Sie einen USB-Barcode-Scanner an und scannen Sie das Medikament – oder geben Sie den Code ein.",
       "scannedTitle": "Barcode gescannt",
       "cancel": "Abbrechen",
       "submit": "Artikel hinzufügen",

frontend/lib/i18n/locales/en/translation.json

@@ -697,7 +697,7 @@
       "expires": "Expires",
       "barcode": "Barcode / NDC",
       "barcodePlaceholder": "Scan or type a code",
-      "scan": "Scan barcode",
+      "scanHint": "Connect a USB barcode scanner and scan the medication — or type the code.",
       "scannedTitle": "Barcode scanned",
       "cancel": "Cancel",
       "submit": "Add item",

frontend/lib/i18n/locales/fr/translation.json

@@ -697,7 +697,7 @@
       "expires": "Expire le",
       "barcode": "Code-barres / NDC",
       "barcodePlaceholder": "Scanner ou saisir un code",
-      "scan": "Scanner le code-barres",
+      "scanHint": "Branchez un lecteur de code-barres USB et scannez le médicament — ou saisissez le code.",
       "scannedTitle": "Code-barres scanné",
       "cancel": "Annuler",
       "submit": "Ajouter l'article",

frontend/lib/i18n/locales/so/translation.json

@@ -697,7 +697,7 @@
       "expires": "Dhacaya",
       "barcode": "Barcode / NDC",
       "barcodePlaceholder": "Iskaan garee ama qor koodh",
-      "scan": "Iskaan garee barcode",
+      "scanHint": "Ku xir iskaanka barcode-ka USB oo iskaan garee daawada — ama qor koodhka.",
       "scannedTitle": "Barcode la iskaan gareeyay",
       "cancel": "Jooji",
       "submit": "Ku dar shay",