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>

backend/src/modules/invoices/invoices.service.ts

@@ -64,8 +64,8 @@ export class InvoicesService {
       );
 
       // Create journal entry: DR Accounts Receivable, CR Assessment Income
-      const arAccount = await this.tenant.query(`SELECT id FROM accounts WHERE account_number = 1200`);
-      const incomeAccount = await this.tenant.query(`SELECT id FROM accounts WHERE account_number = 4000`);
+      const arAccount = await this.tenant.query(`SELECT id FROM accounts WHERE account_number = '1200'`);
+      const incomeAccount = await this.tenant.query(`SELECT id FROM accounts WHERE account_number = '4000'`);
 
       if (arAccount.length && incomeAccount.length) {
         const je = await this.tenant.query(