feat(usage-script): add User-Agent header to New API template

Align the New API usage query template with the GENERAL template by
including "User-Agent: cc-switch/1.0" in its request headers, so
cc-switch requests are identifiable in provider server logs and less
likely to be blocked by UA-based rate limiting on some New API
deployments.

src/components/UsageScriptModal.tsx

@@ -73,6 +73,7 @@ const generatePresetTemplates = (
     headers: {
       "Content-Type": "application/json",
       "Authorization": "Bearer {{accessToken}}",
+      "User-Agent": "cc-switch/1.0",
       "New-Api-User": "{{userId}}"
     },
   },