DHT support

Similar to torrent's DHT solution, required features:
- Find peer to specified site file (to allow sites to add optionally download files)
- Ipv6 and tor address support for peers
- It should work using on Tor (TCP only, maybe UDP on clearnet)
- No other library dependency if possible
- Store peer ips to allow work without bootstrap server

Maybe its requred to separate the DHT from Peer Exchange

Please comment if you have other ideas/suggestions.

Start by reviewing the existing Peer Exchange and bootstrap-server paths, then map how peer discovery and stored peer IPs are handled. Check the current entry points for site-file downloads and Tor, TCP/UDP, and IPv6 support before proposing a DHT boundary. Done requires an agreed design covering peer discovery, persistence, transport support, and dependency constraints.

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