ci: keep the issue-welcome run in Actions history

The job deleted its own run once the comment was posted, so a failure to
post left nothing behind to look at. Keep the run, and drop the
`actions: write` permission it needed only in order to delete itself.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.github/workflows/issue-welcome.yml

@@ -6,7 +6,6 @@ on:
 
 permissions:
   issues: write
-  actions: write
 
 jobs:
   supporter-priority-note:
@@ -23,9 +22,3 @@ jobs:
 
           If you support OpenCADStudio on [Patreon](https://www.patreon.com/HakanSeven12), send me either your GitHub username or this issue number in a Patreon message. After I verify your support, I will prioritize the issue.
           EOF
-
-      - name: Remove this run from Actions history
-        env:
-          GH_TOKEN: ${{ github.token }}
-          GH_REPO: ${{ github.repository }}
-        run: gh api --method DELETE "repos/$GH_REPO/actions/runs/$GITHUB_RUN_ID"