GHSA-33jq-p8c2-q3q4: SiYuan: Unauthenticated SQL injection in searchDocs via unescaped keyword (publish mode): cross-notebook read/write with statement stacking

The /api/filetree/searchDocs endpoint concatenates the caller-supplied search keyword directly into a SQL statement with no escaping and no parameter binding. The endpoint is gated by CheckAuth only reachable by the publish RoleReader token, and by the anonymous account when Publish.Auth.Enable is false. The resulting statement runs on a read-write SQLite handle through a driver that executes stacked (;-separated) statements, against the global blocks table spanning all cleartext notebooks. An unauthenticated request can therefore read and write database content across every non-encrypted notebook on the instance.