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/pages/DesignGuide.tsx

@@ -1061,7 +1061,7 @@ export function DesignGuide() {
           <div className="text-foreground">[12:00:17] INFO  Reconnected successfully</div>
           <div className="flex items-center gap-1.5">
             <span className="relative flex h-1.5 w-1.5">
-              <span className="absolute inline-flex h-full w-full rounded-full bg-cyan-400 animate-ping" />
+              <span className="absolute inline-flex h-full w-full rounded-full bg-cyan-400 animate-pulse" />
               <span className="inline-flex h-full w-full rounded-full bg-cyan-400" />
             </span>
             <span className="text-cyan-400">Live</span>