docs: update site copy to match repositioned README

[sonukapoor]

Aligns docs/index.html with the developer-first framing introduced in the README rewrite.

• Hero paragraph now leads with the problem before the solution, matching the README narrative
• Features section heading updated to "Built for the developer, not the pipeline"
• Footer opens with the closing line from the README: "Most tools tell you what's wrong. CVE Lite CLI tells you what to run."

Closes #242