Add TRANSFER transaction type with bulk action and auto-rules

- Add TRANSFER to TransactionType enum; excluded from cash flow queries
- Add TransferRule model: description patterns that auto-mark transactions
  as transfers on upload (takes priority over budget rules)
- Bulk action "Mark as transfer" in transaction table
- Transfer Rules button/dialog on transactions page for managing patterns
- Transfers shown with ⇄ prefix and muted color in transaction list

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

src/app/(app)/dashboard/page.tsx

@@ -32,6 +32,7 @@ export default async function DashboardPage({ searchParams }: { searchParams: Se
       JOIN "Account" a ON t."accountId" = a.id
       WHERE a."userId" = ${userId}
         AND a.type = 'BANK'
+        AND t.type != 'TRANSFER'
         AND t.date >= ${start}
         AND t.date <= ${end}
       GROUP BY t.type