feat: add tracking for auth request success and failure counts

- Introduced `Success` and `Failed` fields in auth records to track request outcomes.
- Updated `/v0/management/auth-files` and `/v0/management/api-key-usage` responses to include success and failure counts.
- Enhanced tests to validate tracking logic and API responses.

internal/api/handlers/management/auth_files.go

@@ -388,6 +388,8 @@ func (h *Handler) buildAuthFileEntry(auth *coreauth.Auth) gin.H {
 		"source":         "memory",
 		"size":           int64(0),
 	}
+	entry["success"] = auth.Success
+	entry["failed"] = auth.Failed
 	entry["recent_requests"] = auth.RecentRequestsSnapshot(time.Now())
 	if email := authEmail(auth); email != "" {
 		entry["email"] = email