fix: use heredoc to avoid quoting issues in PR comment

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

.github/workflows/llm-hello-world.yaml

@@ -128,20 +128,24 @@ jobs:
       - name: Post comment to PR
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          SUMMARY: ${{ steps.llm.outputs.summary }}
+          AUTHOR: ${{ steps.pr.outputs.author }}
+          PR_NUM: ${{ inputs.pr_number }}
         run: |
-          echo "Posting comment to PR #${{ inputs.pr_number }}..."
+          echo "Posting comment to PR #$PR_NUM..."
 
-          COMMENT="## LLM Hello World Test
+          gh pr comment "$PR_NUM" --body "$(cat <<EOF
+          ## LLM Hello World Test
 
           **Model:** \`$LLM_MODEL\`
-          **PR Author:** @${{ steps.pr.outputs.author }}
+          **PR Author:** @$AUTHOR
 
           ### Summary
-          ${{ steps.llm.outputs.summary }}
+          $SUMMARY
 
           ---
-          *This comment was generated by the LLM Hello World workflow (Phase 0a)*"
-
-          gh pr comment ${{ inputs.pr_number }} --body "$COMMENT"
+          *This comment was generated by the LLM Hello World workflow (Phase 0a)*
+          EOF
+          )"
 
           echo "Comment posted successfully!"