Fix: Hard-coded checklist items in dangerfile.js don't match PR template

## Summary

The `requiredChecklistItems` array in `dangerfile.js` contains hard-coded checklist strings that don't match the actual PR template checklist items. This causes compliant PRs to be incorrectly flagged by the Danger CI check.

## Problem

The current strings in `dangerfile.js` are:
- `"My PR addresses a single issue"`
- `"My code follows the project's code style"`
- `"My changes generate no new warnings or errors"`

However, the actual PR template checklist contains different text, causing false negatives.

## Proposed Fix

Update `requiredChecklistItems` to exactly match the PR template text, or implement tolerant/label-based matching (case-insensitive, whitespace-normalized) to avoid future drift.

## References

- PR: https://github.com/AOSSIE-Org/Template-Repo/pull/111
- Review comment: https://github.com/AOSSIE-Org/Template-Repo/pull/111#discussion_r3005886058

Reported by: @kpj2006