GO-2026-6452 Panic via negative shared-string index in github.com/xuri/excelize

In github.com/xuri/excelize/v2, parsing a spreadsheet cell with a negative shared-string index causes a runtime panic. The shared-string lookup in xlsxC.getValueFrom checks only the upper bound of the parsed index against the shared-string slice length, causing negative indices such as -1 to bypa...