Credibility and trust improvements (wave 1)

We shipped the first wave of credibility improvements on the marketing site:

• Trustpilot proof on home, PRO home, and partners pages, with honest review context
• Security headers (Permissions-Policy, COOP, CORP) and a security.txt endpoint
• Structured data for articles, coaches, pricing, and videos
• Article bylines with author metadata and refreshed company-first About content

These changes make claims easier to verify without adding marketing fluff.