fix(invoices): real empty states in the editor pickers (#1678)

Zero customers rendered the customer Select as a bare few-pixel sliver;
it now shows 'Inga kunder än'. The supplier menu showed an orphan
separator above its create action when no suppliers exist; it now shows
'Inga leverantörer än' and drops the separator. The row-entry suggestion
hint loses its top border when no article list renders above it.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

messages/en.json

@@ -3487,6 +3487,7 @@
     "bank_add_now": "Add now",
     "customer_card_title": "Customer",
     "select_customer_placeholder": "Select customer",
+    "no_customers_yet": "No customers yet",
     "create_customer": "Create customer",
     "create_customer_dialog_title": "Add customer",
     "create_customer_failed_title": "Could not create customer",
@@ -4250,6 +4251,7 @@
     "paid_privately_help_ef": "Booked as a liability from the company to you (2018 Egen insättning). Refund manually later from the company account.",
     "paid_privately_help_ab": "Booked as a liability from the company to you (2893 Skuld till ägare). Refund manually later from the company account.",
     "supplier_placeholder": "Select supplier",
+    "no_suppliers_yet": "No suppliers yet",
     "add_new_supplier": "+ Add new supplier...",
     "supplier_invoice_number_label": "Supplier's invoice number",
     "supplier_invoice_number_placeholder": "Invoice no. from supplier",

messages/sv.json

@@ -3487,6 +3487,7 @@
     "bank_add_now": "Lägg till nu",
     "customer_card_title": "Kund",
     "select_customer_placeholder": "Välj kund",
+    "no_customers_yet": "Inga kunder än",
     "create_customer": "Skapa kund",
     "create_customer_dialog_title": "Lägg till kund",
     "create_customer_failed_title": "Kunde inte skapa kund",
@@ -4250,6 +4251,7 @@
     "paid_privately_help_ef": "Bokförs som skuld från bolaget till dig (2018 Egen insättning). Återbetalas senare manuellt från företagskontot.",
     "paid_privately_help_ab": "Bokförs som skuld från bolaget till dig (2893 Skuld till ägare). Återbetalas senare manuellt från företagskontot.",
     "supplier_placeholder": "Välj leverantör",
+    "no_suppliers_yet": "Inga leverantörer än",
     "add_new_supplier": "+ Lägg till ny leverantör...",
     "supplier_invoice_number_label": "Leverantörens fakturanummer",
     "supplier_invoice_number_placeholder": "Fakturanr från leverantören",