test(tools): stop the tty session before removing its root

TestExecCommandTTYSkipsInteractiveBlock runs ssh to a bogus host under
tty with a 250ms yield. When ssh is still resolving the host after the
yield, the session keeps running in the test's directory and nothing
stops it, so on Windows t.TempDir's cleanup fails with a sharing
violation. It failed Smoke (windows-latest) on a README-only PR.

Stop the session in a cleanup, and build the tool on execTestRoot,
which retries the removal while Windows still holds the directory right
after the stop, as the other exec tests that leave a session do.

internal/tools/exec_command_test.go

@@ -936,8 +936,15 @@ func TestExecCommandInteractiveBlockSuggestsTTY(t *testing.T) {
 }
 
 func TestExecCommandTTYSkipsInteractiveBlock(t *testing.T) {
-	tool := NewScopedExecCommandTool(t.TempDir(), nil, newExecSessionManager())
-	// ssh to a bogus host fails fast on its own; the point is that the
+	// The ssh can still be resolving the bogus host when the 250ms yield
+	// returns, which leaves its session running in the test root. Stop it
+	// before the root goes, and use execTestRoot for the moment Windows still
+	// holds the directory after the stop.
+	root := execTestRoot(t)
+	manager := newExecSessionManager()
+	t.Cleanup(func() { manager.StopAll() })
+	tool := NewScopedExecCommandTool(root, nil, manager)
+	// ssh to a bogus host fails on its own; the point is that the
 	// interactive guard must not fire ahead of the tty path.
 	result := tool.Run(context.Background(), map[string]any{
 		"cmd": "ssh host.example.com", "tty": true, "yield_time_ms": 250,