v2.0.25

perf(daemon): mark all pieces verified when adding torrent in seed mode

libtorrent's seed_mode triggers a lazy async_hash on every piece the
first time a peer requests it (peer_connection.cpp 5298), to defend
against on-disk corruption between the time the torrent was created
and the time we start seeding.

For ezio's typical use case — partclone or similar generates the raw
image and the torrent in one step, then ezio seeds that exact image —
the source data is trusted by construction, and that lazy verify just
re-reads + re-hashes the whole 60+ GiB image as peers ask for pieces.
In 1-on-1 cold runs we measured ~48s of wall time (40% of elapsed)
spent on this verify pass; in 1-to-3 cold the cost is ~6s.

libtorrent provides a per-torrent knob for exactly this: filling
add_torrent_params::verified_pieces with all-true bits marks every
piece as already verified, so the lazy-verify branch in peer_connection
is skipped and async_read is reached directly.

Scope:
- Only takes effect when seeding_mode=true (the gRPC AddTorrent flag).
  Leecher behaviour is unchanged — they still hash every downloaded
  piece against the torrent's expected SHA1.
- No gRPC API change. Existing AddTorrent semantics remain the same;
  callers that don't want this behaviour can simply not add the torrent
  in seeding mode.

Expected gain:
- 1-on-1 cold:  122s -> ~74s    (+65% throughput, matches warm-seeder)
- 1-to-3 cold:  172s -> ~165s   (+3-4% throughput)
- multi-peer deployments (Clonezilla Lite-Server style) benefit most
  on the seeder CPU side, less on wall clock.

Signed-off-by: Date Huang <tjjh89017@hotmail.com>