fix(dashboard): keep Android keyboard open in main chat; disable kanban pinch-zoom

Two Android-specific fixes:

1. Keyboard dismissing in main chat. App.tsx derives `mobileKeyboardOpen`
   from useMobileKeyboard and uses it to gate the
   `project-content--with-mobile-nav` / `--with-footer` className
   assignment plus MobileNavBar rendering. When the soft keyboard opened
   on Android, those classes were removed and the nav unmounted, shrinking
   padding-bottom by ~80px in a single render. Android Chrome treats the
   resulting jump of the focused chat input as the focus target moving and
   instantly dismisses the keyboard. With interactive-widget=resizes-content
   set on Android, the layout viewport itself shrinks with the keyboard, so
   the hide-nav-on-keyboard pattern was redundant on Android (and harmful).
   The whole pattern is now gated to iOS via isIOS(). iOS path is unchanged.

2. Pinch-zoom on kanban. Android Chrome ignores user-scalable=no for a11y,
   and kanban's overflow-x:auto columns combined with the inflated ICB
   produce a broken visual when the user zooms out. Adds
   touch-action: pan-x pan-y to html,body inside the mobile media query
   (keeps scroll panning, blocks pinch-zoom). Chat and MissionManager were
   unaffected before because they don't expose a wide horizontal
   scrollable region.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/styles.css

@@ -3219,6 +3219,11 @@ input[type="range"]:focus-visible {
   html,
   body {
     overflow: hidden;
+    /* Disable pinch-zoom on mobile — Android Chrome ignores user-scalable=no
+       for a11y, and the kanban board's horizontally-scrollable layout
+       interacts badly with zoom-out (exposes the offscreen-right area).
+       `pan-x pan-y` keeps scroll panning but blocks pinch-zoom. */
+    touch-action: pan-x pan-y;
   }
 
   #root {