feat(invoices): create customer & supplier invoices in modals, matching the verifikat pattern (#861)

Invoice and supplier-invoice creation now open as pop-up dialogs on their
list pages instead of navigating to standalone form pages — the same UX as
NewJournalEntryDialog (capped-height scroll, explicit-close-only so a
half-typed invoice survives stray Escape/backdrop clicks).

- InvoiceEditor gains a `bare` variant (page chrome stripped, inline actions
  replacing the fixed mobile bar, live document-type title kept) hosted by
  the new NewInvoiceDialog (sm:max-w-5xl). Draft editing pages unchanged.
- The 2,057-line supplier form moves out of the route page into
  components/supplier-invoices/NewSupplierInvoiceForm.tsx with
  bare/inboxItemId/onCreated/onCancel props, hosted by
  NewSupplierInvoiceDialog (sm:max-w-4xl).
- Modals are URL-driven (?new=1): header buttons, empty states, command
  palette, and the reports CTA all open the same dialog; browser back
  closes it. /invoices/new and /supplier-invoices/new survive as redirects
  (bookmarks, agent intents, /expenses/new alias, inbox deep links).
- The invoice-inbox "Skapa leverantörsfaktura" action opens the modal in
  place and refreshes the inbox on success instead of navigating away.

No new i18n keys; dialog titles reuse existing strings.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/ui/empty-state.tsx

@@ -99,7 +99,7 @@ export function EmptyState({
 
 // Preset empty states for common pages
 
-export function EmptyInvoices() {
+export function EmptyInvoices({ onAction }: { onAction?: () => void } = {}) {
   const t = useTranslations('empty')
   return (
     <EmptyState
@@ -107,7 +107,8 @@ export function EmptyInvoices() {
       title={t('preset_invoices_title')}
       description={t('preset_invoices_description')}
       actionLabel={t('preset_invoices_action')}
-      actionHref="/invoices/new"
+      actionHref={onAction ? undefined : '/invoices?new=1'}
+      onAction={onAction}
     />
   )
 }
@@ -186,7 +187,7 @@ export function EmptyReports() {
       title={t('preset_reports_title')}
       description={t('preset_reports_description')}
       actionLabel={t('preset_reports_action')}
-      actionHref="/invoices/new"
+      actionHref="/invoices?new=1"
       secondaryActionLabel={t('preset_reports_secondary')}
       secondaryActionHref="/import"
     />