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/ActiveAgentsPanel.tsx

@@ -434,7 +434,7 @@ function AgentRunCard({
         <div className="flex items-center gap-2 min-w-0">
           {isActive ? (
             <span className="relative flex h-2 w-2 shrink-0">
-              <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>
           ) : (