- Add 2-byte dlen prefix to terminal BATCH/HASHES data so receiver knows
exact byte count — fixes rem=0 bug that truncated multi-item BATCHes.
- Fix synthetic HASHES prefix_bytes: use merkle_sync_prefix_bytes(next_lvl)
for both declaration and _prefix_write, not current level's pb_i.
- Fix initiator never getting _session_done: responder sends confirmation
HASHES(is_data=1,level=0) before _session_done so initiator's done_cb fires.
- Add level==0 guard in _member_get_items/_member_update_bucket_hash
to prevent SQL queries with bogus mask on virtual root level.
Evgeny
6bf8482558