Two changes to the Redox minimal input backend patch:
1. read_input_line accumulated into a *fresh* String each retry. On the
Redox console pty, a `read_line` can return WouldBlock (or Ok(0))
after only a partial line — the characters just typed — and those
bytes, left in the read_line buffer, were discarded on every retry.
Only a fully-queued line (e.g. a leftover newline) ever came through,
so the shell echoed keystrokes but never executed the command.
Fix: accumulate partial reads into a thread-local buffer that
persists across retries and only yield a line once a newline arrives.
2. Removed all BRUSH-DBG / rb_dbg startup and read tracing (the "debug
mode" output on the console). The functional Redox changes stay:
tokio current-thread runtime and the minimal input backend selection.
Verified: brush-interactive + brush-shell compile. Runtime verification
of the interactive shell still pending a boot test.
vasilito
5c9bce4b88