console: one sequential loop; host tests in one binary

The console reads a line, runs it to the end, and prints the result,
with and without a terminal. Notifications print while a command runs.
Ctrl-C during a command stops only the wait. 314 lines (was 480).

All host integration tests are modules of cli/tests/host/, so they run
in one parallel pool, and the probes build once. Warm, the 184 host
tests take 24 s (was about 45 s as seven binaries in sequence), and
cargo test --workspace takes 45 s.

cli/tests/host/main.rs

@@ -0,0 +1,9 @@
+//! Host integration contracts run in one parallel libtest pool.
+mod activation;
+mod agent;
+mod cargo;
+mod cli;
+mod common;
+mod console;
+mod core;
+mod sdk;