feat: add bank file import as core, move Enable Banking to extension

Replace PSD2 bank integration as the default with file-based bank
import (CSV/XML), which better suits Swedish sole traders and small
companies. Enable Banking is now an opt-in extension.

- Phase 1: Extract generic transaction ingestion service (ingest.ts)
  with dedup, auto-categorization, and OCR-based invoice matching
- Phase 2: Bank file parser library supporting Nordea, SEB, Swedbank,
  Handelsbanken CSV formats and ISO 20022 camt.053 XML
- Phase 3: Database migration adding import_source, reference columns
  and bank_file_imports tracking table
- Phase 4: Import wizard UI (5-step flow) and API routes for parse/execute
- Phase 5: Move Enable Banking to extensions/enable-banking/ with
  commented-out loader entry for opt-in activation
- Phase 6: 104 new tests (ingestion + all parser formats), fixing
  Nordea detection overlap and camt.053 XML tag collision bugs

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

lib/invoice/invoice-matching.ts

@@ -11,6 +11,7 @@ export interface InvoiceMatch {
  * Confidence thresholds for invoice matching
  */
 const CONFIDENCE = {
+  OCR_REFERENCE_MATCH: 0.99,
   EXACT_AMOUNT_CUSTOMER: 0.95,
   EXACT_AMOUNT_ONLY: 0.80,
   FUZZY_AMOUNT_CUSTOMER: 0.70,
@@ -144,6 +145,29 @@ export async function findMatchingInvoices(
 
   const matches: InvoiceMatch[] = []
 
+  // OCR/Bankgiro reference matching — highest confidence
+  // Swedish standard: match transaction reference to invoice OCR number
+  const txReference = (transaction as Transaction & { reference?: string | null }).reference
+  if (txReference) {
+    const normalizedRef = txReference.replace(/\s+/g, '')
+    for (const invoice of invoices) {
+      // Match against invoice_number (used as OCR reference in Swedish payments)
+      const invoiceRef = invoice.invoice_number?.replace(/\s+/g, '')
+      if (invoiceRef && normalizedRef === invoiceRef) {
+        matches.push({
+          invoice: invoice as Invoice & { customer?: Customer },
+          confidence: CONFIDENCE.OCR_REFERENCE_MATCH,
+          matchReason: `OCR-referens matchar fakturanummer ${invoice.invoice_number}`,
+        })
+      }
+    }
+
+    // If we found an OCR match, return immediately (highest possible confidence)
+    if (matches.length > 0) {
+      return matches
+    }
+  }
+
   for (const invoice of invoices) {
     // Currency filter - must match or be SEK equivalent
     const currencyMatch =