feat(contacts): add contacts module with feedback form
- public /contacts page with contact info (email, phone, address, working hours, socials) and Schema.org markup
- feedback form with captcha for guests, honeypot, CSRF/flood/ban checks and consent checkboxes
- contact_messages table, admin list with status filter, message view, mark as processed and delete
- admin settings stored in the johncms config: multilingual texts with current language / site default / english fallback
- admin notification via the EmailMessage queue with a new mail template
- install/install_contacts.php for existing sites