fix: match actual Netlify 'Draft URL: <url>' output format

Agent-Logs-Url: https://github.com/nextcloud/documentation/sessions/09c9207a-a095-4936-bfa5-ea1de5218fd8

Co-authored-by: skjnldsv <14975046+skjnldsv@users.noreply.github.com>

Author: Copilot

.github/workflows/sphinxbuild.yml

@@ -634,16 +634,19 @@ jobs:
         continue-on-error: true
         run: |
           set +e
-          json=$(netlify deploy \
+          output=$(netlify deploy \
             --dir=netlify-deploy \
             --site="${{ secrets.NETLIFY_SITE_ID }}" \
             --auth="${{ secrets.NETLIFY_AUTH_TOKEN }}" \
             --alias="pr-${{ github.event.pull_request.number }}" \
-            --message="Preview for PR #${{ github.event.pull_request.number }}" \
-            --json 2>/dev/null)
+            --message="Preview for PR #${{ github.event.pull_request.number }}" 2>&1)
           exit_code=$?
-          echo "$json"
-          preview_url=$(echo "$json" | jq -r '.deploy_url // .url // ""' 2>/dev/null || echo "")
+          echo "$output"
+          # Strip ANSI codes, then extract the URL from "Draft URL: <https://...>"
+          preview_url=$(printf '%s\n' "$output" \
+            | sed 's/\x1b\[[0-9;]*[mGKHFJABCDsuKl]//g' \
+            | grep -oP '(?:Draft URL|Website Draft URL|Website URL):\s+<?https://\K[^>\s]+' \
+            | head -1)
           echo "url=${preview_url}" >> "$GITHUB_OUTPUT"
           exit $exit_code