list_discussions and get_discussion should include upvoteCount

Summary

The list_discussions and get_discussion tools currently return metadata like title, created_at, updated_at, and comments.totalCount, but omit upvoteCount. This field is available on the Discussion type in GitHub's GraphQL API and is the primary signal for gauging community demand on a feature request.

Use case

When using these tools to triage feature request discussions (e.g. scanning a repo's FR backlog as a PM), vote count is a critical prioritisation input. Without it, the only available proxy for demand is comment count or last-activity date — both of which are noisy signals (a thread with 2 comments and 400 upvotes looks identical to one with 2 comments and 3 upvotes).

Proposed change

Add upvoteCount to the GraphQL query used by both list_discussions and get_discussion. The field is already on the Discussion type:

discussion(number: 48) {
  upvoteCount   # add this
  title
  createdAt
  updatedAt
  comments { totalCount }
}

No new permissions are required — upvoteCount is accessible with the existing read:discussion scope.

Expected output

{
  "number": 48,
  "title": "Open letter for improving Home Assistant's Authentication system",
  "upvoteCount": 412,
  "created_at": "2025-06-22T10:18:35Z",
  "updated_at": "2026-05-01T09:12:00Z"
}