Adds «6.4 Рекомендация по продукту» to Section6Forecast — the §13.4
product recommendation (class, unit-mix, commercial, USP, §16 reasons)
that previously existed only in the export renderers. Unit-mix is shown
as token-colored horizontal bars; since the assembler emits no per-format
share (pct), bars are honestly labeled as a deficit-by-format signal, not
a build-share. Graceful on thin/202-pending/partial reports.
- types/forecast.ts: ReportProductTz + nested interfaces, optional on ForecastReport
- ForecastProductTzBlock.tsx: per-field guards, role=img bars, reasons disclosure
- forecast-helpers.ts: deficitBarWidthPct
- Section6Forecast + sidebar nav: wire 6.4
Part of #958.
