fix: lock body scroll and re-add programmatic terminal touch scroll

- Add body.terminal-page-open { overflow: hidden } to prevent page scroll
- TerminalPage adds/removes 'terminal-page-open' class on body when mounted
- Re-add capture-phase touch listeners in terminal.tsx with low 3px threshold
- Call e.preventDefault() immediately when vertical gesture is detected,
  before browser compositor commits to page scroll
- Remove CSS touch-action overrides on xterm viewport (now handled in JS)
- Scroll forwarded via term.scrollLines() with 24px per line sensitivity

apps/web/src/styles.css

@@ -77,6 +77,10 @@ body {
 	color: var(--ink);
 }
 
+body.terminal-page-open {
+	overflow: hidden;
+}
+
 [data-theme="dark"] body {
 	background: radial-gradient(circle at top right, #2a2520, var(--bg));
 }
@@ -3709,14 +3713,6 @@ a.nav-item,
 
 /* xterm.js manages its own scrolling and viewport dimensions */
 
-/* Mobile: enable native touch scrolling on xterm viewport */
-.terminal-wrapper.mobile .xterm .xterm-viewport {
-	touch-action: pan-y !important;
-	-webkit-overflow-scrolling: touch !important;
-	overflow-y: auto !important;
-	scrollbar-width: none;
-}
-
 /* Special Keys Strip */
 .special-keys-strip {
 	flex-shrink: 0;