fix: remove all touch interception, let browser scroll xterm viewport natively

- xterm.js has zero touch event handlers (verified: only 1 'touch' ref in
  entire library), so it wasn't intercepting anything
- Our touch-action: none + preventDefault() combo was blocking the browser
  from scrolling the .xterm-viewport natively
- Removed all custom touch event handlers from terminal.tsx
- Removed touch-action: none from .terminal-container
- Added touch-action: pan-y to .xterm-viewport so browser allows vertical pan
- Body scroll lock (terminal-page-open) prevents page from scrolling

apps/web/src/styles.css

@@ -3707,13 +3707,17 @@ a.nav-item,
 	padding: 0;
 	overflow: hidden;
 	position: relative;
-	touch-action: none;
 }
 
 /* xterm.js manages its own sizing */
 
 /* xterm.js manages its own scrolling and viewport dimensions */
 
+/* Mobile: allow native vertical touch panning on xterm viewport */
+.terminal-wrapper.mobile .xterm .xterm-viewport {
+	touch-action: pan-y;
+}
+
 /* Special Keys Strip */
 .special-keys-strip {
 	flex-shrink: 0;