ZIP/DOCX etc. download natively — no need to force attachment; and the
157 MB Second Brain Vault archive must stream from Caddy with Range,
not through the app. Proxy attachment stays for small inline types (PDF/images).
Direct CDN links opened PDFs inline (no Content-Disposition), which reads
as 'can't download' behind popup blockers / on mobile. New proxy route
streams the file with attachment + human name; lesson link points to it.
admins