[codex] Align feature documentation buttons

[mikitahimpel]

Summary

Align the three documentation buttons in the landing page feature block so they sit on the same baseline.

Why

The feature cards contain different amounts of text. Because each button previously followed its card content naturally, the buttons could appear at different vertical levels across the row. This made the block feel visually uneven.

Changes

• Make each feature column a full-height vertical flex container with justify-between.
• Keep the buttons self-start so the link border stays content-width instead of stretching across the column.

Visual check

Before	After

Validation

• pnpm check
• pnpm build

Note: pnpm build still reports existing warnings about outdated Browserslist data and missing metadataBase, but completes successfully.