Add SEO optimization and Schema.org structured data for Fortinet comparison page

SEO Enhancements:
- Update title to include year (2025) for freshness signal
- Optimize meta description with focus on FortiGate vulnerabilities
- Add TechArticle Schema.org for technical content ranking
- Add dynamic FAQPage Schema.org for rich snippets in search results

Content Improvements:
- Add Key Takeaways section with 4 critical points (Architecture, Resilience, Transparency, Cost)
- Standardize product naming throughout: Fortinet (company), FortiGate (appliance), FortiClient (endpoint)
- Emphasize FortiGate as specific target of COATHANGER malware (20,000+ devices compromised)
- Update Strategic Difference table headers for clarity

New Components:
- TechArticleJSONLD.astro - Schema.org for technical articles with publication date
- FAQPageJSONLD.astro - Dynamic FAQ schema generation from page content

Enhanced Sections:
- Setup: Distinguish test environment (one-line install) from production (Docker/K8s/Terraform)
- Cost: Add mandatory support contracts, link to VPN MFA page
- Security: Precise FortiGate vulnerability references with external links to CVE-2024-21762 and Volt Typhoon
- FAQ: Add new question about open-source security advantages
- Architecture: Update diagram to GitBook hosted image

Link Updates:
- ACL documentation: Fixed to correct docs.defguard.net/features/access-control-list
- MFA link: Added to vpn_mfa page in Cost section
- All deployment guides updated with correct paths

Author: piotr-bor