Fix PowerPoint font embedding issues in PDF export by patching text transparency in PPTX files. Use when a user has a PPTX file where exported PDFs show wrong/default fonts instead of the intended downloaded/custom fonts, even with font embedding enabled. Works by applying minimal (1%) transparency to fully-opaque text runs, which forces PowerPoint to properly embed fonts during PDF export.

通过为PPTX文件中的文本应用透明度补丁来修复PDF导出时的字体嵌入问题。当用户遇到PPTX文件导出的PDF显示错误或默认字体，而非预期的已下载或自定义字体（即使已启用字体嵌入）时使用。该方法通过对完全不透明的文本段应用极小（1%）的透明度，强制PowerPoint在导出PDF时正确嵌入字体。