Add taxableFlag to product updates, QUO-Narrative quote fallback, and orphan reconciliation

- Add taxableFlag boolean field to product update schema and forecast patch
- Fall back to QUO-Narrative product customerDescription for quote narrative
- Reconcile orphaned local opportunity records not found in CW during refresh
- Invalidate caches for removed orphaned opportunities
- Add reconciled event and orphanedCount to refresh events
- Update API_ROUTES.md with taxableFlag field documentation

src/api/sales/opportunities/[id]/products/update.ts

@@ -18,6 +18,7 @@ const updateProductSchema = z
     customerDescription: z.string().nullable().optional(),
     productNarrative: z.string().nullable().optional(),
     procurementNotes: z.string().nullable().optional(),
+    taxableFlag: z.boolean().optional(),
   })
   .strict()
   .refine(
@@ -108,6 +109,9 @@ export default createRoute(
         (input.unitCost * effectiveQuantity).toFixed(2),
       );
     }
+    if (input.taxableFlag !== undefined) {
+      forecastPatch.taxableFlag = input.taxableFlag;
+    }
 
     const existingProcurement =
       await opportunity.fetchProcurementProductByForecastItem(productId);