docs: tighten landing page and support matrix

[peg]

Summary

• align rampart.sh landing copy with the current docs and v0.9.22 product state
• make the support matrix readable on laptop/mobile by replacing the wide table with responsive cards
• tighten mobile wrapping and wording on the landing page quickstart/install sections

What changed

• update landing SEO/meta/version copy and quickstart messaging
• add clearer support-matrix/configuration/OpenClaw links from the landing page
• make landing install/setup blocks wrap cleanly on smaller screens
• restyle getting-started/support-matrix.md into responsive support cards

Verification

• reviewed local landing preview at laptop/mobile widths
• reviewed local support matrix preview at laptop/mobile widths
• mkdocs build completes (existing d2 warnings/errors still present in unrelated docs build paths)