fix(import): parse the SEB Transaktioner CSV layout (split Insättningar/Uttag) (#1616)

* fix(import): parse the SEB Transaktioner CSV layout (split Insättningar/Uttag)

The SEB profile only understood the Kontoutdrag export layout. The
Transaktioner page (the path most users find first) exports a different
header: Bokförd;Valutadatum;Text;Typ;Insättningar;Uttag;Bokfört saldo,
with dot decimals and the amount split across two columns. No profile
detected it, so auto-detection found nothing and an explicit SEB choice
failed on column detection.

Teach the SEB profile the layout: detect on the Insättningar/Uttag pair
(unique among supported formats), accept Bokförd as a booking-date
column, and combine the split amount (Uttag carries its own minus;
unsigned magnitudes are normalized to expenses). Fixture header and
first data row are verbatim from a user-provided export. The import
help text now lists both SEB export paths.

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

* docs: decision log for SEB Transaktioner parser design

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>

components/import/BankFileUploadStep.tsx

@@ -235,7 +235,7 @@ export default function BankFileUploadStep({
           <div>
             <p className="font-medium">SEB</p>
             <p className="text-muted-foreground">
-              Logga in → Konton → Kontoutdrag → Hämta som fil (CSV)
+              Logga in → Konton → Transaktioner → Exportera (CSV), eller Kontoutdrag → Hämta som fil (CSV)
             </p>
           </div>
           <div>