fix(ci): handle multi-line PR body in linked issues check

Use heredoc to safely write PR body to temp file instead of storing in variable.
This prevents bash from interpreting special characters and multi-line content
as commands (exit code 127 error).

Fixes workflow failure in PR #3.

.github/workflows/pr-into-dev.yml

@@ -80,14 +80,18 @@ jobs:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           PR_NUMBER="${{ github.event.pull_request.number }}"
-          PR_BODY="${{ github.event.pull_request.body }}"
 
           echo "Checking for linked issues in PR #$PR_NUMBER"
 
+          # Write PR body to temp file to handle multi-line content safely
+          cat > /tmp/pr_body.txt << 'EOF'
+          ${{ github.event.pull_request.body }}
+          EOF
+
           # Check for keywords like "Closes", "Fixes", "Resolves", "Relates to"
           ISSUE_KEYWORDS="Closes|Fixes|Resolves|Relates to|Ref|References"
 
-          if echo "$PR_BODY" | grep -qiE "($ISSUE_KEYWORDS) #[0-9]+"; then
+          if grep -qiE "($ISSUE_KEYWORDS) #[0-9]+" /tmp/pr_body.txt; then
             echo "✅ Found linked issue(s) in PR body"
             echo "has-linked-issues=true" >> $GITHUB_OUTPUT
           else