fix(maestro): bind terminal touch scroll to .xterm

The touch handlers sat on `.xterm-viewport`, but xterm appends the
absolutely-positioned viewport before the `position: relative` screen, so
`.xterm-screen` paints over it and takes every touch. The viewport is not an
ancestor of the screen, so the listeners never fired and mobile drags did
nothing. Moves them, and `touch-action: none`, to `.xterm`.

web/src/styles.css

@@ -1332,10 +1332,12 @@ input.leaf-rename:focus {
 .attach-body .xterm .xterm-viewport {
   overflow-y: auto;
   scrollbar-width: none;
-  /* Maestro drives scrollback from touchmove (see attach.ts). `pan-y` hands
-     the gesture to the browser, which may cancel the event stream before the
-     terminal sees it; `none` keeps a drag inside the terminal under our
-     control while the rest of the page retains native scrolling. */
+}
+
+/* Maestro drives scrollback from touchmove (see attach.ts), so the browser must
+   not claim the gesture. On `.xterm`, not the viewport: `.xterm-screen` paints
+   over the viewport and is what a finger lands on. */
+.attach-body .xterm {
   touch-action: none;
 }