一份 PDF 的最后一公里：合并、盖水印、签字、转图The last mile of a PDF — merge, watermark, sign, export
合同、扫描件、报价单凑成一份发出去，真正麻烦的从来不是「生成 PDF」，而是最后那几步：顺序、页码、水印、签名，还有对方到底能不能打开。Merging a contract, a scan and a quote into one file is easy; the last mile — order, page numbers, watermark, signature, and whether the other side can even open it — is the part that bites.