Root cause of "the TUI keeps rendering after I get my terminal back": on
quit, dispose() called logSink.releaseConsole() (re-pointing console.* at
the real terminal) and then tui.stop() left the alt-screen and restored the
user's shell. Every log line from the slow engine/mesh/dev-server teardown
that followed then painted over the recovered prompt.
dispose() now calls a new logSink.silence() instead, which drops all sink
and console.* output from quit through process exit. Shutdown-step
diagnostics (timeShutdownStep + the watchdog stall line) are gated behind
FUSION_DEBUG_SHUTDOWN so a normal quit is pristine; the 3s hard-exit
watchdog still guarantees the process dies.
Adds a silence() regression guard to log-sink.test.ts asserting sink
methods and captured console.* both go silent across surfaces.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>