fix(opencode): avoid TTY corruption from double cleanup (#16565)

Co-authored-by: Shoubhit Dash <[email protected]>

packages/opencode/src/cli/cmd/tui/thread.ts

@@ -208,7 +208,6 @@ export const TuiThreadCommand = cmd({
             prompt,
             fork: args.fork,
           },
-          onExit: stop,
         })
       } finally {
         await stop()