ci: remove Quad9 DNS monitor

Quad9 now resolves pkg.claude-desktop-debian.dev to Cloudflare IPs;
the hourly check is no longer needed.

Co-Authored-By: Claude <claude@anthropic.com>

.github/workflows/dns-monitor-quad9.yml

@@ -1,46 +0,0 @@
-name: DNS Monitor — Quad9 block on pkg.claude-desktop-debian.dev
-
-on:
-  schedule:
-    - cron: '0 * * * *'
-  workflow_dispatch:
-
-permissions:
-  issues: write
-  actions: write
-
-jobs:
-  check:
-    runs-on: ubuntu-latest
-    env:
-      ISSUE: '524'
-      DOMAIN: pkg.claude-desktop-debian.dev
-      GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-    steps:
-      - name: Resolve via Quad9
-        id: dig
-        run: |
-          ip=$(dig +short "$DOMAIN" @9.9.9.9)
-          ts=$(date -u '+%Y-%m-%d %H:%M UTC')
-          if [[ -z "$ip" ]]; then
-            line="- ❌ ${ts} — NXDOMAIN on Quad9 (still blocked)"
-            echo "resolved=false" >> "$GITHUB_OUTPUT"
-          else
-            line="- ✅ ${ts} — resolved to ${ip} on Quad9 — @aaddrick domain is back, stopping monitor"
-            echo "resolved=true" >> "$GITHUB_OUTPUT"
-          fi
-          echo "line=$line" >> "$GITHUB_OUTPUT"
-
-      - name: Append to issue body
-        env:
-          LINE: ${{ steps.dig.outputs.line }}
-        run: |
-          body=$(gh issue view "$ISSUE" --repo "$GITHUB_REPOSITORY" --json body -q .body)
-          new_body="${body}"$'\n'"${LINE}"
-          gh issue edit "$ISSUE" --repo "$GITHUB_REPOSITORY" --body "$new_body"
-
-      - name: Disable workflow on resolution
-        if: steps.dig.outputs.resolved == 'true'
-        run: |
-          gh workflow disable .github/workflows/dns-monitor-quad9.yml \
-            --repo "$GITHUB_REPOSITORY"