Update sonar-check.yml to manage coverage comments (#13878)

.github/workflows/sonar-check.yml

diff --git a/.github/workflows/sonar-check.yml b/.github/workflows/sonar-check.yml
index fbb3cb9..7f2a1bd 100644
--- a/.github/workflows/sonar-check.yml
+++ b/.github/workflows/sonar-check.yml
@@ -80,12 +80,14 @@
             const emojiMap  = { A: '🟢', B: '🟡', C: '🟠', D: '🔴', F: '⛔' };
             const emoji     = emojiMap[grade] ?? '❓';
             const runUrl    = `${context.serverUrl}/${context.repo.owner}/${context.repo.repo}/actions/runs/${context.runId}`;
+            const marker    = '<!-- coverage-grade-bot -->';
 
             const branchRow = branchPct !== 'N/A'
               ? `| Branch coverage | **${branchPct}%** |`
               : '';
 
             const body = [
+              marker,
               `## ${emoji} Test Coverage Grade: \`${grade}\` — ${label}`,
               '',
               '| Metric | Value |',
@@ -106,10 +108,26 @@
               `> [View full Actions run](${runUrl})`,
             ].filter(l => l !== undefined).join('\n');
 
-            await github.rest.issues.createComment({
+            const { data: comments } = await github.rest.issues.listComments({
               owner:        context.repo.owner,
               repo:         context.repo.repo,
               issue_number: context.issue.number,
-              body:         body,
             });
-            console.log('Posted coverage grade comment');
+            const existing = comments.find(c => c.user.login === 'github-actions[bot]' && c.body.includes(marker));
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner:      context.repo.owner,
+                repo:       context.repo.repo,
+                comment_id: existing.id,
+                body:       body,
+              });
+              console.log('Updated existing coverage grade comment');
+            } else {
+              await github.rest.issues.createComment({
+                owner:        context.repo.owner,
+                repo:         context.repo.repo,
+                issue_number: context.issue.number,
+                body:         body,
+              });
+              console.log('Posted coverage grade comment');
+            }