feat(ui): give every panel one scrollbar, select and slider skin

Every scrolling surface carries the kit's .ui-scroll, which
draws the thin themed scrollbar from --scroll-thumb and --scroll-track; the
Context panel and others drew the platform's light scrollbar because the
page declares no dark color-scheme. The per-panel scrollbar rules go; Cyber
sets the two tokens and Cockpit's HUD windows keep their accent tint.

Selects draw .gev-field's own chevron instead of the platform arrow, the
voice selects join .gev-field, number fields keep dark spinners, and the
Street Level range uses the shared slider in its green.

src/ui/views/CommandDockView.vue

@@ -22,7 +22,7 @@ function selectMapSource(chip) {
 
 <template>
   <!-- Unified bottom command dock: locations, voice (injected at runtime), visual presets -->
-  <div id="command-dock" aria-label="Navigation, voice, and visual preset controls" data-i18n-aria-label>
+  <div id="command-dock" class="ui-scroll" aria-label="Navigation, voice, and visual preset controls" data-i18n-aria-label>
   <!-- Control panel -->
   <div id="control-panel" class="panel-collapsible collapsed">
     <div class="panel-glow"></div>