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>

types/index.ts

@@ -157,6 +157,17 @@ export interface BankAccount {
   balance: number | null
 }
 
+// Import source identifiers
+export type ImportSource =
+  | 'enable_banking'
+  | 'csv_nordea'
+  | 'csv_seb'
+  | 'csv_swedbank'
+  | 'csv_handelsbanken'
+  | 'csv_generic'
+  | 'camt053'
+  | 'manual'
+
 // Transaction
 export interface Transaction {
   id: string
@@ -198,6 +209,10 @@ export interface Transaction {
   // Receipt link
   receipt_id: string | null
 
+  // Import tracking
+  import_source: string | null
+  reference: string | null  // OCR number, Bankgiro reference
+
   // Notes
   notes: string | null
 
@@ -205,6 +220,27 @@ export interface Transaction {
   updated_at: string
 }
 
+// Bank File Import (tracking table for file-based imports)
+export type BankFileImportStatus = 'pending' | 'processing' | 'completed' | 'failed'
+
+export interface BankFileImport {
+  id: string
+  user_id: string
+  filename: string
+  file_hash: string
+  file_format: string
+  transaction_count: number
+  imported_count: number
+  duplicate_count: number
+  matched_count: number
+  date_from: string | null
+  date_to: string | null
+  status: BankFileImportStatus
+  error_message: string | null
+  created_at: string
+  updated_at: string
+}
+
 // Customer
 export interface Customer {
   id: string