perf(invoices): the invoice editor renders on the first paint from the session cache (#1937)

"Ny faktura" was the slowest form to fill in: the list page lazy-loaded
NewInvoiceDialog, which lazy-loaded InvoiceEditor (ssr:false), which then
issued four requests on mount (customers, articles, chart of accounts,
company settings) and hid the ENTIRE form behind a spinner until the
customers query alone resolved, even though the other three had landed.
Reopening the dialog paid all of it again.

- InvoiceEditor reads customers, articles, posting accounts and settings
  from lib/reference-data (seeded by the dashboard layout). The whole-form
  spinner gate is gone; the customer picker shows "Hämtar kunder ..." only
  while the list is genuinely uncached. Company settings are applied once
  per editor instance through a guarded effect, so a background
  revalidation can never re-run the create-mode prefills over notes or a
  reference the user has typed. Inline customer/article creation
  invalidates the shared cache (awaited, so the new option resolves before
  the line points at it). Customers now come through /api/customers, which
  masks the personnummer column; nothing in the editor rendered it.
- NewInvoiceDialog imports the editor statically: the dialog is itself a
  next/dynamic chunk on the list page, so this is one deferred chunk
  download when the dialog opens instead of two sequential ones.
- New strings: invoice_editor.loading_customers (sv + en).

Per "Ny faktura": 2 sequential chunk loads -> 1; blocking mount requests
4 -> 0 (cached) with every field populated on the first render.
raw-reference-fetch ratchet: 46 -> 45 files. SendInvoiceDialog and
PaymentBookingDialog (init() flows) stay in the baseline for a later PR.

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

scripts/checks/antipatterns-baseline.json

@@ -34,7 +34,7 @@
     ]
   },
   "rawReferenceFetch": {
-    "count": 46,
+    "count": 45,
     "files": [
       "app/(dashboard)/assets/[id]/dispose/page.tsx",
       "app/(dashboard)/bookkeeping/year-end/page.tsx",
@@ -62,7 +62,6 @@
       "components/import/FiscalYearGapNotice.tsx",
       "components/import/ImportReviewStep.tsx",
       "components/import/OpeningBalancePeriodStep.tsx",
-      "components/invoices/InvoiceEditor.tsx",
       "components/invoices/PaymentBookingDialog.tsx",
       "components/invoices/SendInvoiceDialog.tsx",
       "components/pending-operations/use-account-names.ts",