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/MetricCard.tsx

@@ -18,7 +18,7 @@ export function MetricCard({ icon: Icon, value, label, description, to, onClick
     <div className={`h-full px-4 py-4 sm:px-5 sm:py-5 rounded-lg transition-colors${isClickable ? " hover:bg-accent/50 cursor-pointer" : ""}`}>
       <div className="flex items-start justify-between gap-3">
         <div className="flex-1 min-w-0">
-          <p className="text-2xl sm:text-3xl font-semibold tracking-tight">
+          <p className="text-2xl sm:text-3xl font-semibold tracking-tight tabular-nums">
             {value}
           </p>
           <p className="text-xs sm:text-sm font-medium text-muted-foreground mt-1">