Hojun-Cho
e10e95321f
bstream wraps *io.stream with caller-supplied rbuf/wbuf; init, flush, setflush, unread, isbuffered, bread, bwrite, bclose mirror ref/hare/bufio/stream.ha modulo the bstream-vs-stream rename (cross-module type collision, see task #21). Default flush byte-set is "\n" (Hare flag::NONE default at stream.ha:75). Drops the prior ww-only FLUSH_ON_WRITE flag for Hare's flush []u8 + setflush byte-set. bufiotest.ww adds 10 @test fns: small-write, auto-flush, line-flush default, manual-flush, isbuffered, unread (post-read and pre-read budgets), scanner-over-bstream unread, flush-empty no-op, bclose flushes, setflush custom byte.