features
  finish syncing
    * logging of bytes up/down
    * up/both directions
    * error handling and reporting
    * way to close sync request
    * limit on number of concurrent sync requests
    * full-db scan limited by since/until
    * `strfry sync` command always takes at least 1 second due to batching delay. figure out better way to flush
  bool values in config
    config for compression
    config for TCP keepalive
  db versioning
  document config options, detailed default config file
  less verbose default logging
  nice new config "units" feature, ie 1d instead of 86400
  make it easier for a thread to setup a quadrable env
  opt: PubkeyKind scans could be done index-only

rate limits
  slow-reader detection and back-pressure
  max connections per ip (nginx?)
  max bandwidth up/down (nginx?)
  event writes per second per ip
  max number of concurrent REQs per connection/ip
  ? limit on total number of events from a DBScan, not just per filter

misc
  periodic reaping of disconnected sockets
  ? websocket-level pings