feat: display Copilot premium interactions quota on provider card

Copilot usage query API was implemented but never surfaced on the main
provider list. Add CopilotQuotaFooter component that auto-detects
github_copilot providers and displays premium interaction utilization
inline, reusing the existing TierBadge UI from SubscriptionQuotaFooter.

src/components/SubscriptionQuotaFooter.tsx

@@ -22,6 +22,8 @@ export const TIER_I18N_KEYS: Record<string, string> = {
   gemini_flash_lite: "subscription.geminiFlashLite",
   // Token Plan（five_hour 已在上方官方映射中）
   weekly_limit: "subscription.weeklyLimit",
+  // GitHub Copilot
+  premium: "subscription.copilotPremium",
 };
 
 /** 根据使用百分比返回颜色 class */