Extends the probe binary so it can do more than verify tracker reach:
when given a real file, it builds a single-file torrent in memory,
seeds it via the WebTorrent peer wire, and prints the magnet URI
(with the WSS tracker injected). Useful for proving the end-to-end
streaming path before any actual unarr daemon work lands.
Internally uses anacrolix/torrent's metainfo.Info.BuildFromFilePath
+ bencode.Marshal to mint InfoBytes, then AddTorrent → seed loop.
Piece length picked from a libtorrent-like ladder (16 KiB → 4 MiB)
so the resulting torrent is interoperable with mainstream clients.
Validation: synthesised a 5 s 320×240 H.264+AAC mp4 with ffmpeg
(`testsrc + sine`), seeded it via this binary against the production
wss://tracker.torrentclaw.com endpoint, opened the in-browser player
at /stream/<info_hash>. Browser reported `downloaded: 105 KB / 105 KB`
and rendered a working <video> with controls. Seeder reported
`uploaded=107452 bytes`. Pieces flowed P2P over WebRTC data channel,
zero relay through TorrentClaw infrastructure.
Closes the manual half of Fase 4.4 of the streaming plan; the
companion player change (file.blob() in place of the v2-removed
file.renderTo) is committed separately on the web side.
2aeabe6b50