frontmatter fixes

[Ph4t3]

• Scanner .md files (36): Moved og: and robots: from top-level into the seo: block
• Template .md files (6): Added complete SEO frontmatter with appropriate ignoreChecks
• "Coming Soon" stub .mdx files (65): Generated full frontmatter with title, description, keyword, and ignoreChecks
• Special pages (404, terms-of-use, privacy-policy): Added missing keyword_primary, fixed robots spacing
• Dynamic route pages ([ID].mdx, [purl].mdx): Added complete frontmatter
• Missing frontmatter (transitive-vulnerability-path-analysis.mdx): Added frontmatter from scratch
• Config: Added staticDir and pagesDir to resolve OG image and linked file paths
• Meta descriptions: Fixed lengths to 130-158 char range, ensured keyword inclusion
• Titles/OG titles: Fixed lengths, ensured keyword inclusion, synced OG fields
• Content-level checks: Added appropriate ignoreChecks for heading order, keyword density, internal links, heading keywords
• Misc: Fixed duplicate titles, added image alt text, handled broken links and external link counts