feat(import): import skattekontoutdrag files into the skattekonto pipeline (#1637)

* feat(import): import skattekontoutdrag files into the skattekonto pipeline

Users can now upload the kontohändelse export from Skatteverket's
skattekonto e-service (current CSV layout, verified against a real
2026-08 export, plus legacy .skv files) instead of needing the paid API
connection. Parsed rows land in skattekonto_transactions as booked
file_import rows and inherit the existing 1630 rules engine, bulk
booking, match-to-verifikat and both UIs unchanged.

- Core parser lib/import/skattekonto-file/ with strict detection
  (orgnr header + saldo markers, or two distinct SKV vocabulary terms
  plus row shape), sum-integrity check (opening + rows must equal
  closing) and a wrong-company guard against company_settings.
- computeDedupKey moves to core (lib/skatteverket/skattekonto-dedup);
  the extension re-imports it. File rows hash-key; content-signature
  partitioning skips rows already booked (either key form) and promotes
  matching upcoming rows in place.
- syncSkattekonto gains a takeover step: an id-keyed API row adopts a
  matching hash-keyed imported row in place, so journal links survive
  connecting the API after a file import. Upcoming rows can no longer
  clobber a booked row on hash collision.
- New skattekonto_file_imports table (company-scoped file-hash dedup)
  plus source/file_import_id provenance columns on
  skattekonto_transactions.
- /import gains a Skattekontoutdrag wizard (upload/preview/result,
  deep link ?mode=skattekonto); the bank-file flow detects skattekonto
  files and redirects instead of importing them as bank rows.
- /skattekonto renders imported rows for unconnected companies (attn
  line + import CTA) instead of discarding them behind the StartCard.
- Free for everyone: the local-data booking/match routes were already
  ungated; only API sync/saldo stay capability-gated.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(skattekonto): align the EF F-skatt rule with the 2012 -> 2013 decision

20260810120000 established that 2012 is not standard BAS and moved the
booking templates to 2013 (owner taxes in an enskild firma are an eget
uttag), but the skattekonto_rules seed still booked EF preliminarskatt
against 2012. The file importer makes this rule fire for every EF
F-skatt row, so bring it onto 2013 too.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* fix(import): apply review findings on the skattekonto file import

- Fix the takeover candidate comparator: the single-argument sort was an
  inconsistent relation and could adopt a stale upcoming row ahead of the
  booked file row in a 3+ candidate queue (regression test added), and
  page the candidate scan with fetchAllRows so a multi-year window is not
  silently capped at 1000 rows.
- Fail parsing when a statement HAS saldo markers but not both readable
  balances: a file cut off before "Utgående saldo" previously skipped the
  sum check entirely. sum_valid stays null only for marker-less legacy
  files.
- Count a promotion only when the UPDATE matched a row, so a concurrent
  sync cannot inflate promoted_count; log a failed finalize of the import
  record instead of discarding the error.
- Migration (unshipped, edited in place): user_id is nullable with
  ON DELETE SET NULL so import records and their file-hash dedup survive
  user deletion, and the INSERT policy binds user_id to auth.uid() so a
  member cannot attribute an import to a colleague. pg tests cover both.
- Make the upload drop zone keyboard-reachable (role, tabIndex, Enter/
  Space) and give the six count-bearing strings ICU plural forms in both
  locales.

Skipped with reasons on the PR: binding execute rows to file bytes and
re-checking orgnr in execute (same client-trust model as the shipped
bank-file execute; Zod + RLS scope writes to the caller's own company),
a 404 test (the route has no not-found path), event-bus clearing in the
route test (the route touches no events), and FK NOT VALID (new column
referencing a brand-new empty table).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

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

lib/errors/structured-errors.ts

@@ -1686,6 +1686,65 @@ const BANK_FILE: Record<string, StructuredErrorEntry> = {
     message_sv: 'Bankfilsimporten misslyckades.',
     message_en: 'Bank file import failed.',
   },
+  BANK_FILE_SKATTEKONTO_DETECTED: {
+    httpStatus: 400,
+    message_sv:
+      'Filen ser ut som ett skattekontoutdrag från Skatteverket. Använd Skattekonto-importen i stället.',
+    message_en:
+      'This file looks like a Skatteverket tax account statement. Use the skattekonto import instead.',
+  },
+}
+
+const SKATTEKONTO_FILE: Record<string, StructuredErrorEntry> = {
+  SKATTEKONTO_FILE_NO_FILE: {
+    httpStatus: 400,
+    message_sv: 'Ingen fil bifogad i förfrågan.',
+    message_en: 'No file attached to the request.',
+  },
+  SKATTEKONTO_FILE_TOO_LARGE: {
+    httpStatus: 400,
+    message_sv: 'Filen är för stor. Maxstorlek är 10 MB.',
+    message_en: 'File exceeds the 10 MB size limit.',
+  },
+  SKATTEKONTO_FILE_DUPLICATE: {
+    httpStatus: 409,
+    message_sv: 'Det här kontoutdraget har redan importerats.',
+    message_en: 'This tax account statement has already been imported.',
+  },
+  SKATTEKONTO_FILE_PARSE_FAILED: {
+    httpStatus: 500,
+    message_sv: 'Kunde inte tolka skattekontoutdraget.',
+    message_en: 'Failed to parse the tax account statement.',
+  },
+  SKATTEKONTO_FILE_NOT_RECOGNIZED: {
+    httpStatus: 400,
+    message_sv:
+      'Filen känns inte igen som ett skattekontoutdrag. Ladda ner kontohändelserna från Skatteverkets e-tjänst Skattekonto och försök igen.',
+    message_en:
+      'The file was not recognized as a tax account statement. Download the account events from Skatteverket and try again.',
+  },
+  SKATTEKONTO_FILE_SUM_MISMATCH: {
+    httpStatus: 400,
+    message_sv:
+      'Utdraget summerar inte: ingående saldo plus händelser stämmer inte med utgående saldo. Filen kan vara ofullständig.',
+    message_en:
+      'The statement does not sum: opening balance plus events does not equal the closing balance. The file may be incomplete.',
+  },
+  SKATTEKONTO_FILE_NO_ROWS: {
+    httpStatus: 400,
+    message_sv: 'Kontoutdraget innehåller inga händelser att importera.',
+    message_en: 'No account events to import.',
+  },
+  SKATTEKONTO_FILE_IMPORT_RECORD_FAILED: {
+    httpStatus: 500,
+    message_sv: 'Kunde inte skapa importpost.',
+    message_en: 'Failed to create the import record.',
+  },
+  SKATTEKONTO_FILE_EXECUTE_FAILED: {
+    httpStatus: 500,
+    message_sv: 'Importen av skattekontoutdraget misslyckades.',
+    message_en: 'Tax account statement import failed.',
+  },
 }
 
 const OPENING_BALANCE_IMPORT: Record<string, StructuredErrorEntry> = {
@@ -3584,6 +3643,7 @@ const REGISTRY: Record<string, StructuredErrorEntry> = {
   ...TAX_DECL,
   ...SIE_IMPORT,
   ...BANK_FILE,
+  ...SKATTEKONTO_FILE,
   ...OPENING_BALANCE_IMPORT,
   ...REGISTER_IMPORT,
   ...PROVIDER_MIGRATION,