generateCSV escaped quotes only when a value happened to contain a comma and never neutralised formula prefixes, so every CSV log export could emit attacker controlled cells that execute when an admin opens the file. actor is a virtual API key name validated as nothing more than a non-empty string, and path, host, originalRequestURL, metadata and the AI session bodies come straight from the client request.
Each value now goes through a single encoder that collapses CR, LF and CRLF to a literal \n so a record can never be split across rows, prefixes a leading apostrophe when the first character would make a spreadsheet evaluate the cell as a formula, and quotes whenever the field contains a comma or a quote instead of only when it contains a comma. Headers use the same encoder so a column name cannot desynchronise the rows from the header row.
The five CSV export endpoints also declare charset=utf-8, matching the content type already used by the log streaming destination.
Fixes#3864