Add a sound

Upload any audio file and it becomes a catalog candidate. Provenance is required rather than optional: the licence is resolved against the shipped licence policy, and the source URL plus the source's own id are kept so the row can be traced back years later. The file is decoded on the server and the original is discarded.

Uploading does not add anything to the catalog. It puts the audio where the loop finder can reach it, and the promote step afterwards proves, against the live catalog, that the result is the live bytes plus exactly one appended row.