Flexible budget import with auto-account creation and text-based account numbers

Change account_number from INTEGER to VARCHAR(50) to support segmented codes
like 30-3001-0000 used by real HOA accounting systems. Budget CSV import now:
- Auto-creates income/expense accounts from CSV when they don't exist
- Infers account_type and fund_type from account number prefix conventions
- Parses currency-formatted values ($48,065.21, $(13,000.00), $-, etc.)
- Reports created accounts back to the user

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

frontend/src/pages/reports/IncomeStatementPage.tsx

@@ -6,7 +6,7 @@ import { DateInput } from '@mantine/dates';
 import { useQuery } from '@tanstack/react-query';
 import api from '../../services/api';
 
-interface AccountLine { account_number: number; name: string; amount: string; fund_type: string; }
+interface AccountLine { account_number: string; name: string; amount: string; fund_type: string; }
 interface IncomeStatementData {
   from: string; to: string;
   income: AccountLine[]; expenses: AccountLine[];