feat: arcim migration wizard UX, import fixes, Sentry setup (#22)

* feat: import system improvements, INK2 fix, and Swedish text corrections

- 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>

* feat: arcim migration wizard UX fixes, Sentry setup, and extension scaffolding

Arcim migration wizard improvements:
- Progress bar now excludes non-interactive steps (migrating/result)
- Fix OAuth text to match target="_blank" behavior (new tab, not redirect)
- Display month names instead of "Månad X" in preview
- Fix Swedish typo "förifylla" in no-company-info message
- Replace native checkboxes with shadcn Switch in options step
- Add ConfirmationDialog before starting migration
- Show progress percentage during migration
- Add "Nästa steg" guidance and navigation links in result step
- Add "Försök igen" button in error state (returns to options)
- Add Bokio company ID help text (GUID from URL)
- Add Fortnox integration add-on hint on connection failure

Also includes: SIE import system improvements, INK2 fixes, Swedish text
corrections, Sentry error tracking setup, and arcim-migration extension
scaffolding.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: address PR review feedback

- Fix OAuth error recovery blank page (restore provider from URL params)
- Pass real userId to MigrationWizard instead of empty string
- Remove ~50 debug console.log statements from sie-import.ts
- Fix comment referencing account 3740 → 3741

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

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

app/api/import/sie/[id]/route.ts

@@ -40,7 +40,12 @@ export async function GET(
 
 /**
  * DELETE /api/import/sie/[id]
- * Delete an import record (does not delete created journal entries)
+ * Delete an import record.
+ *
+ * Only failed or pending imports can be deleted. Completed imports have created
+ * journal entries that are part of räkenskapsinformation — deleting the metadata
+ * without reversing entries would leave orphaned bookkeeping data, and deleting
+ * both is prohibited under BFL 7 kap (7-year retention).
  */
 export async function DELETE(
   request: Request,
@@ -57,6 +62,24 @@ export async function DELETE(
     return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
   }
 
+  // Check current status before deleting
+  const { data: importRecord } = await supabase
+    .from('sie_imports')
+    .select('status')
+    .eq('id', id)
+    .eq('user_id', user.id)
+    .single()
+
+  if (!importRecord) {
+    return NextResponse.json({ error: 'Import not found' }, { status: 404 })
+  }
+
+  if (importRecord.status === 'completed') {
+    return NextResponse.json({
+      error: 'Slutförd import kan inte raderas. Importerade verifikationer ingår i räkenskapsinformationen (BFL 7 kap).',
+    }, { status: 403 })
+  }
+
   const { error } = await supabase
     .from('sie_imports')
     .delete()

app/api/import/sie/parse/route.ts

@@ -7,7 +7,7 @@ import {
   decodeBuffer,
   calculateFileHash,
 } from '@/lib/import/sie-parser'
-import { suggestMappings, getMappingStats } from '@/lib/import/account-mapper'
+import { suggestMappings, getMappingStats, isSystemAccount } from '@/lib/import/account-mapper'
 import { generateImportPreview, checkDuplicateImport } from '@/lib/import/sie-import'
 import { BAS_REFERENCE } from '@/lib/bookkeeping/bas-data'
 import type { SIEAccountMappingRecord } from '@/lib/import/types'
@@ -78,6 +78,15 @@ export async function POST(request: Request) {
       }, { status: 400 })
     }
 
+    // Separate source-system internal accounts (e.g. Fortnox 0099) from
+    // real bookkeeping accounts. System accounts have no BAS equivalent and
+    // should not appear in the mapping step.
+    const excludedSystemAccounts = parsed.accounts
+      .filter((a) => isSystemAccount(a.number))
+      .map((a) => ({ number: a.number, name: a.name }))
+    const bookkeepingAccounts = parsed.accounts
+      .filter((a) => !isSystemAccount(a.number))
+
     // Fetch stored mappings from database
     const { data: storedMappings } = await supabase
       .from('sie_account_mappings')
@@ -88,13 +97,15 @@ export async function POST(request: Request) {
     // the user's active chart (~40 accounts). Accounts that match will be
     // auto-activated during the execute step.
     const mappings = suggestMappings(
-      parsed.accounts,
+      bookkeepingAccounts,
       BAS_REFERENCE,
       (storedMappings as SIEAccountMappingRecord[]) || undefined
     )
 
     // Generate preview
     const preview = generateImportPreview(parsed, mappings)
+    preview.excludedSystemAccounts = excludedSystemAccounts
+    preview.accountCount = bookkeepingAccounts.length
 
     // Calculate file hash for storage
     const fileHash = await calculateFileHash(content)