Move webui from /loop/webui to /webui

Thanks, perl (and git mv):

	perl -pi -e s,loop/webui,webui,g $(git grep -l loop/webui)
diff --git a/loop/server/loophttp.go b/loop/server/loophttp.go
index 271375b..e1b76ad 100644
--- a/loop/server/loophttp.go
+++ b/loop/server/loophttp.go
@@ -25,7 +25,7 @@
 	"github.com/creack/pty"
 	"sketch.dev/ant"
 	"sketch.dev/loop"
-	"sketch.dev/loop/webui"
+	"sketch.dev/webui"
 )
 
 // terminalSession represents a terminal session with its PTY and the event channel