chore(deps): upgrade dependencies and clean unused packages

- Upgrade @opennextjs/cloudflare from 1.14.7 to 1.14.8
- Downgrade wrangler from 4.56.0 to 4.35.0
- Remove unused @cspell/dict-it-it package
- Remove unused @types/mdx package
- Change Node engine version from >=22.0.0 to ^22.0.0 for consistency

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

Author: ericyangpan