feat: add token usage tracking and leaderboard

- Add token_usage table with composite unique index for claw_id + date
- Add API endpoints: POST /token, GET /token/leaderboard, GET /token/stats
- Add TokenLeaderboard component with daily/total period toggle
- Add CLI commands: `token` and `stats` for reporting and viewing usage
- Add Redis caching for leaderboard with 1-minute TTL
- Add shared utilities: authenticateRequest, getTodayDateString
- Use UPSERT pattern for atomic token updates
- Add i18n translations (en/zh) for new UI elements

app/[locale]/page.tsx

@@ -12,6 +12,7 @@ import { StatsPanel } from "@/components/dashboard/stats-panel";
 import { ActivityTimeline } from "@/components/dashboard/activity-timeline";
 import { ClawFeed } from "@/components/dashboard/claw-feed";
 import { RegionRanking } from "@/components/dashboard/region-ranking";
+import { TokenLeaderboard } from "@/components/dashboard/token-leaderboard";
 import { cn } from "@/lib/utils";
 
 const WorldMap = dynamic(
@@ -55,6 +56,7 @@ export default function HomePage() {
             <div className="flex flex-col gap-4">
               <StatsPanel />
               <RegionRanking />
+              <TokenLeaderboard />
             </div>
 
             {/* Center - Map/Globe + Timeline */}