Fix capability box height consistency

[Martinnn674]

Summary

• Switch the capability section to a two-column CSS grid at desktop breakpoints.
• Stretch grid rows and the inner capability cards so the boxes stay the same height across the desktop layout.
• Keep the 1200px breakpoint from shrinking the card minimum height below the 1024px layout.

Fixes #259

Verification

• npm.cmd run lint:css
• npm.cmd run format:check -- docs/styles/home.css docs/components/capability-box/capability-box.module.css
• npm.cmd run test:docs
• Playwright layout check against the local docs site: capability card heights were uniform at 1024px, 1200px, and 1440px.