fix(import): show "created on import" as the mapping target for source accounts the chart lacks (#2342)

The guided Fortnox import self-mapped a source account that exists in
neither the company chart nor BAS (4599) and then rendered its Malkonto
select blank, because the dropdown only knew chart + BAS accounts. The
row looked unmapped and unmappable while the import created the account
correctly. A nameless account (referenced by #TRANS without #KONTO) was
worse: the mapper refused the self-map, so it stayed unmapped with no
self-target to pick.

- account-mapper: the bas_range self-map no longer requires a #KONTO
  name; unmapped now means exactly "outside 1000-8999". isValidBASRange
  exported as the auto-create boundary.
- AccountMappingStep (shared by both wizards): a target the list cannot
  name is an explicit "<nr> <name> (skapas vid importen)" option, a
  "nya konton skapas" badge/filter lists them, out-of-range accounts
  that block Continue are named, nameless sources say so.
- sie-import: skippedVouchers.unmappedAccounts (per account, voucher
  count) via summarizeUnmappedSkips; warning names the accounts.
- Migration result step: names created accounts and the accounts behind
  "med ej kopplade konton".

Closes #2212


Claude-Session: https://claude.ai/code/session_019SaJfqNi4VmsG8FMKq99G6

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

messages/en.json

@@ -5492,7 +5492,12 @@
     "vat_review_filter": "{count} VAT treatments to review",
     "vat_treatment_column": "VAT treatment",
     "vat_treatment_confirm": "Confirm",
-    "vat_treatment_confirm_help": "Accept the VAT code for this row to mark it as reviewed. Change the VAT code or rate first if the suggestion is wrong."
+    "vat_treatment_confirm_help": "Accept the VAT code for this row to mark it as reviewed. Change the VAT code or rate first if the suggestion is wrong.",
+    "new_account_filter": "{count} new accounts to create",
+    "new_account_option": "created on import",
+    "source_name_missing": "no name in the file",
+    "unmapped_out_of_range_help": "Accounts outside the BAS range 1000-8999 cannot be created automatically. Choose which account in the chart their postings should go to: {accounts}.",
+    "mapping_new_accounts_note": "Accounts missing from the chart are created on import with the name from the source system and the type derived from the account number."
   },
   "dimensions": {
     "new_value": "New value",
@@ -5662,6 +5667,7 @@
     "ext_email_description": "Send invoices and reminders via email",
     "ext_email_long_description": "Enables email features: send invoices to customers, automatic payment reminders on your chosen schedule, and email notifications. Requires a Resend account with a verified domain or your own SMTP server.",
     "ext_arcim_migration_name": "System migration",
+    "ext_arcim_accounts_created": "{count, plural, one {# new account was added to the chart of accounts with its name from the source system.} other {# new accounts were added to the chart of accounts with names from the source system.}}",
     "ext_arcim_registration_links_label": "Voucher links",
     "ext_arcim_registration_links_value": "{linked} of {scanned} invoices linked to their booking voucher",
     "ext_arcim_registration_links_detail": "{unlinked} not linked: {noRef} without a voucher number at the provider, {refNotFetched} whose provider details could not be fetched in time, {unresolved} without an unambiguous booking voucher, {amountMismatch} with a differing amount",

messages/sv.json

@@ -5492,7 +5492,12 @@
     "vat_review_filter": "{count} momskoder att granska",
     "vat_treatment_column": "Momskod",
     "vat_treatment_confirm": "Bekräfta",
-    "vat_treatment_confirm_help": "Godkänn momskoden för raden så räknas den som granskad. Ändra momskod eller momssats först om förslaget inte stämmer."
+    "vat_treatment_confirm_help": "Godkänn momskoden för raden så räknas den som granskad. Ändra momskod eller momssats först om förslaget inte stämmer.",
+    "new_account_filter": "{count} nya konton skapas",
+    "new_account_option": "skapas vid importen",
+    "source_name_missing": "namn saknas i filen",
+    "unmapped_out_of_range_help": "Konton utanför BAS-intervallet 1000-8999 kan inte skapas automatiskt. Välj vilket konto i kontoplanen deras poster ska bokföras på: {accounts}.",
+    "mapping_new_accounts_note": "Konton som saknas i kontoplanen skapas vid importen med namnet från källsystemet och kontotyp från kontonumret."
   },
   "dimensions": {
     "new_value": "Nytt värde",
@@ -5662,6 +5667,7 @@
     "ext_email_description": "Skicka fakturor och påminnelser via e-post",
     "ext_email_long_description": "Aktiverar e-postfunktioner: skicka fakturor till kunder, automatiska betalningspåminnelser enligt valt schema, och e-postmeddelanden. Kräver ett Resend-konto med verifierad domän eller en egen SMTP-server.",
     "ext_arcim_migration_name": "Systemmigration",
+    "ext_arcim_accounts_created": "{count, plural, one {# nytt konto lades till i kontoplanen med namn från källsystemet.} other {# nya konton lades till i kontoplanen med namn från källsystemet.}}",
     "ext_arcim_registration_links_label": "Verifikatkoppling",
     "ext_arcim_registration_links_value": "{linked} av {scanned} fakturor kopplade till bokföringsverifikat",
     "ext_arcim_registration_links_detail": "{unlinked} utan koppling: {noRef} saknar verifikatnummer hos leverantören, {refNotFetched} vars detaljer inte hann hämtas från leverantören, {unresolved} utan entydigt bokföringsverifikat, {amountMismatch} med avvikande belopp",