[Feature] Company Info & Fiscal Year Reporting Support

## Summary
Explore whether bringing `COMPANY_INFO` — specifically `fiscal_year_start_month` — into `dbt_quickbooks` would provide meaningful additive analytical value to customers, and if so, what the right scope for that support should look like.

## Background
QuickBooks' `CompanyInfo` object exposes `FiscalYearStartMonth`, but the package today has no fiscal-year concept — all period logic (`int_quickbooks__general_ledger_date_spine`, `int_quickbooks__general_ledger_balances`, `int_quickbooks__retained_earnings`) is strictly calendar-year.

## Why we're opening this as a discussion
`CompanyInfo` is usually a single row table. Given that, we want community/customer feedback before investing further:
- Is the `fiscal_year_start_month` field from `CompanyInfo`(and the resulting relabeled `date_year`/period grain it would drive) genuinely useful for financial reporting, or is it a low-value addition given how little new data it actually brings in?
- Is there appetite for extending this beyond year-level grouping to fiscal quarters/periods, which would add more complexity for a still-uncertain payoff?

## What we're soliciting feedback on
1. Would you use fiscal-year-aware reporting in this package if it were available?
2. Would fiscal quarter/period-level grouping (not just year-level) be valuable, or is year-level sufficient?

Start by reviewing the COMPANY_INFO object and the period logic in int_quickbooks__general_ledger_date_spine, int_quickbooks__general_ledger_balances, and int_quickbooks__retained_earnings. The issue is currently seeking feedback rather than defining an implementation. Done would require an agreed scope for fiscal-year reporting, including whether year-level or quarter/period grouping is supported.

Written by the indexing model from the issue text.