fix(ui): scope the wheel-opt-out tooltip's paging fallback to Claude

The reworded tooltip promised the PageUp/PageDown fallback for Claude and
Codex alike, but _localScrollbackIsHollow() gates it to claude mode only
(codex page-key handling is unverified, as the routing tests note). A codex
user reading the old text would flip the setting expecting a rescue and get
a dead wheel instead. Say plainly that Codex has no fallback.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/web/public/index.html

@@ -1322,7 +1322,7 @@
               </div>
               <!-- Input Section -->
               <div class="settings-section-header">Input</div>
-              <div class="settings-item settings-item-multiline" title="Scroll the terminal's own local scrollback with a plain mouse wheel / two-finger swipe, instead of forwarding the wheel to the CLI's transcript. Leave OFF for Claude/Codex sessions: those CLIs redraw the screen in place and keep no local scrollback, so the wheel would have almost nothing to scroll (Codeman falls back to paging the CLI's own transcript). Shift+wheel always reaches local scrollback regardless.">
+              <div class="settings-item settings-item-multiline" title="Scroll the terminal's own local scrollback with a plain mouse wheel / two-finger swipe, instead of forwarding the wheel to the CLI's transcript. Leave OFF for Claude/Codex sessions: those CLIs redraw the screen in place and keep no local scrollback, so the wheel would have almost nothing to scroll. In Claude sessions Codeman then falls back to paging the CLI's own transcript; Codex sessions have no such fallback, so the wheel goes dead. Shift+wheel always reaches local scrollback regardless.">
                 <div class="settings-item-text">
                   <span class="settings-item-label">Wheel Scrolls Local History</span>
                   <span class="settings-item-desc">Plain wheel/trackpad pages the terminal scrollback</span>