fix: update staging deploy PR comment instead of creating duplicates

Include commit SHA in the comment body and reuse the existing comment
on subsequent deploys instead of flooding the PR with new ones.

Author: fengmk2

.github/workflows/ci.yml

@@ -44,9 +44,26 @@ jobs:
         uses: actions/github-script@v7
         with:
           script: |
-            github.rest.issues.createComment({
+            const marker = '<!-- staging-deploy -->';
+            const body = `${marker}\n✅ Staging deployment successful!\n\nPreview: https://vp-setup-staging.void.app/\nCommit: ${context.sha}`;
+            const { data: comments } = await github.rest.issues.listComments({
               owner: context.repo.owner,
               repo: context.repo.repo,
               issue_number: context.issue.number,
-              body: '✅ Staging deployment successful!\n\nPreview: https://vp-setup-staging.void.app/'
-            })
+            });
+            const existing = comments.find(c => c.body.includes(marker));
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: context.issue.number,
+                body,
+              });
+            }