Products with track_inventory=false never create InventoryMovements on sale,
so the old movement-based queries always returned 0. Revenue and units sold
now come from InvoiceItem (the authoritative source for what was actually
invoiced). Stock-in (إجمالي الوارد) still uses InventoryMovement since that
genuinely is a stock-receipt concept. Added إجمالي الإيرادات KPI card.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>