Export a Project's whole ATC library as a CSV file

Bearer atc:read (or cookie session). Columns, fixed order: ATC ID, Slug, Title, Module, Layer, Tags, Status. Multiple Tags for one ATC join into a single cell with ; (semicolon-space). Any cell containing a comma, a double quote, or a line break is RFC4180-quoted, with embedded double quotes doubled. A cell whose content starts with =, +, -, @, a tab, or a CR is prefixed with a literal ' before that escaping, to neutralize spreadsheet formula injection (OWASP guidance). The body is prefixed with a UTF-8 BOM so non-ASCII Title/Tag content renders correctly in Windows Excel. A Project with zero ATCs returns a header-only CSV (200, never an error). No row cap: every non-archived ATC is included regardless of library size.