BeanOS paste-bin — temporary key/value sharing.

  POST   /v1/paste            body = the value (any bytes, <= PASTE_MAX_BYTES)
                              X-Paste-TTL: seconds (default 3600, max 43200)
                              X-Paste-Reads: reads before burn (default 10; 0 = until expiry)
  GET    /<key>               the value (consumes one read)
  HEAD   /<key>               metadata headers only (consumes nothing)
  PUT    /v1/paste/<key>      replace the value (Authorization: Bearer <write_token>)
  DELETE /v1/paste/<key>      Authorization: Bearer <write_token>

Public and unauthenticated: the key is the read secret, the write token the edit secret.