SiYuan: Stored XSS to RCE in SiYuan via a per-attribute URL-scheme sanitizer gap in Lute (form action / SVG xlink:href)

SiYuan is an open-source personal knowledge management system. Prior to 3.7.1, SiYuan renders note and package content to HTML through the Lute engine with sanitization enabled, but Lute's dangerous javascript scheme block does not check form action or SVG xlink:href attributes, allowing stored cross-site scripting in document export-preview and Bazaar package README render paths that can execute OS commands in the Electron desktop renderer. This issue is fixed in versions 3.7.1.