ui: apply interface polish from design article review

- Add global font smoothing (antialiased) to body
- Add tabular-nums to all numeric displays: MetricCard values, Costs page,
  AgentDetail token/cost grids and tables, IssueDetail cost summary,
  Companies page budget display
- Replace markdown image hard border with subtle inset box-shadow overlay
- Replace all animate-ping status dots with calmer animate-pulse across
  AgentDetail, IssueDetail, Agents, sidebar, kanban, issues list, and
  active agents panel

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/components/SidebarNavItem.tsx

@@ -53,7 +53,7 @@ export function SidebarNavItem({
       {liveCount != null && liveCount > 0 && (
         <span className="ml-auto flex items-center gap-1.5">
           <span className="relative flex h-2 w-2">
-            <span className="animate-ping absolute inline-flex h-full w-full rounded-full bg-blue-400 opacity-75" />
+            <span className="animate-pulse absolute inline-flex h-full w-full rounded-full bg-blue-400 opacity-75" />
             <span className="relative inline-flex rounded-full h-2 w-2 bg-blue-500" />
           </span>
           <span className="text-[11px] font-medium text-blue-600 dark:text-blue-400">{liveCount} live</span>