ci(workflow): prevent duplicate comments and hard-fail on missing board assets

- Check for existing bot comment before posting to avoid flooding
- Use github.paginate to fetch all comments (listComments only returns first page)
- Wrap API calls in try-catch to handle rate limits/network errors gracefully
- Changed ::warning to ::error with exit 1 to fail the job when assets are missing
- This blocks PR merge until required assets are added to armbian.github.io

Signed-off-by: Igor Pecovnik <igor@armbian.com>

Author: igorpecovnik

.github/workflows/maintenance-check-board-assets.yml

@@ -143,7 +143,8 @@ jobs:
             echo 'comment<<EOF' >> "$GITHUB_OUTPUT"
             cat "$comment_file" >> "$GITHUB_OUTPUT"
             echo 'EOF' >> "$GITHUB_OUTPUT"
-            echo "::warning ::Missing required assets (see PR comment)."
+            echo "::error::Missing required board assets (see PR comment)."
+            exit 1
           else
             echo "missing=false" >> "$GITHUB_OUTPUT"
           fi
@@ -164,9 +165,30 @@ jobs:
 
             Once the missing files are added (or a PR is opened in **${process.env.WEBSITE_REPO}**), re-run this check.
             `;
-            await github.rest.issues.createComment({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              issue_number: context.issue.number,
-              body
-            });
+
+            // Check if a comment with the same header already exists to avoid flooding
+            // Use paginate to fetch all comments (listComments only returns first page)
+            try {
+              const comments = await github.paginate(github.rest.issues.listComments, {
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: context.issue.number,
+              });
+
+              const botComment = comments.find(comment =>
+                comment.user.type === 'Bot' &&
+                comment.body.includes('### 🚫 Missing required board assets')
+              );
+
+              if (!botComment) {
+                await github.rest.issues.createComment({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  issue_number: context.issue.number,
+                  body
+                });
+              }
+            } catch (error) {
+              // Log error but don't fail the step - the validation already failed with exit 1
+              core.warning(`Failed to post PR comment: ${error.message}`);
+            }