feat(coreping): filter out draft PRs from Core/Important PR notifications (#59)

Draft PRs should not be included in Core/Important PR reminder messages
since they are not ready for review yet. Added check to exclude draft
PRs by marking them as "unrelated" status.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <[email protected]>

Author: snomiao

app/tasks/coreping/index.tsx

@@ -139,6 +139,7 @@ if (import.meta.main) {
 
           if (!corePrLabel) return saveTask({ url: html_url, status: "unrelated" });
           if (pr.state === "closed") return saveTask({ url: html_url, status: "closed" });
+          if (pr.draft) return saveTask({ url: html_url, status: "unrelated", statusMsg: "Draft PR, skipping" });
 
           // check timeline events
           const timeline = await fetchFullTimeline(html_url);