Add a reverse direction to the Booth: the operator (or any client via `curl -F`)
can upload files through the browser and pick them up by a human-readable id.
- POST /upload — streams files to a new booth named with a human-readable id
(e.g. 4-wombat / star-84), 303-redirects to /b/<id>/ (id in the Location
header so curl clients can read it). Uploads reuse the whole booth machinery
(render, per-file download links, 24h TTL sweep, delete).
- Human-readable ids: word+number in either order, collision-checked, from a
curated 140-word friendly list; secrets-based selection.
- Safety: filenames reduced to a safe basename (no traversal), streaming size
cap (BOOTH_MAX_UPLOAD_MB, default 1024) + file-count cap (BOOTH_MAX_FILES,
default 50), partial-write cleanup on any failure.
- UI: Australis-themed upload/drop panel (drag-drop, progressive-enhancement JS,
degrades to a native file input), a "⬆ pickup" badge on upload booths, a
pickup banner, and a ⬇ download link on every gallery item.
- python-multipart dependency; homepage tile description updated; 9 new tests
(24 total, all green).