feat: import system improvements, INK2 fix, and Swedish text corrections (#10)

- SIE parser: Windows-1252 and CP437 encoding detection and decoding
- Bank file parser: add Nordea Business (Företag) CSV format
- Bank file parser: improve format detection for SEB, Länsförsäkringar, generic CSV
- INK2 engine: calculate årets resultat (7222) from income statement for open fiscal years
- Dashboard: parallel Supabase queries, simplified dashboard page
- Fix Swedish characters (å, ä, ö) in BAS data descriptions, validation messages, AI consent disclosures
- Import wizard UI improvements across all steps
- Migration: add 'bas_range' match type to sie_account_mappings constraint
- Extensive new tests for SIE parser encoding and bank file parser

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

supabase/migrations/20260311140000_add_bas_range_match_type.sql

@@ -0,0 +1,10 @@
+-- Add 'bas_range' to the match_type CHECK constraint on sie_account_mappings.
+-- The account-mapper.ts creates mappings with matchType 'bas_range', but the
+-- original CHECK (migration 007) only allowed ('exact', 'name', 'class', 'manual').
+
+alter table sie_account_mappings
+  drop constraint if exists sie_account_mappings_match_type_check;
+
+alter table sie_account_mappings
+  add constraint sie_account_mappings_match_type_check
+    check (match_type in ('exact', 'name', 'class', 'manual', 'bas_range'));