feat(usage): add auto-refresh interval for usage queries

New Features:
- Users can configure auto-query interval in "Configure Usage Query" dialog
- Interval in minutes (0 = disabled, recommend 5-60 minutes)
- Auto-query only enabled for currently active provider
- Display last query timestamp in relative time format (e.g., "5 min ago")
- Execute first query immediately when enabled, then repeat at intervals

Technical Implementation:
- Backend: Add auto_query_interval field to UsageScript struct
- Frontend: Create useAutoUsageQuery Hook to manage timers and query state
- UI: Add auto-query interval input field in UsageScriptModal
- Integration: Display auto-query results and timestamp in UsageFooter
- i18n: Add Chinese and English translations

UX Improvements:
- Minimum interval protection (1 minute) to prevent API abuse
- Auto-cleanup timers on component unmount
- Silent failure handling for auto-queries, non-intrusive to users
- Prioritize auto-query results, fallback to manual query results
- Timestamp display positioned next to refresh button for better clarity

src/components/providers/ProviderCard.tsx

@@ -180,9 +180,11 @@ export function ProviderCard({
       </div>
 
       <UsageFooter
+        provider={provider}
         providerId={provider.id}
         appId={appId}
         usageEnabled={usageEnabled}
+        isCurrent={isCurrent}
       />
     </div>
   );