feat: Add two-cols-footer layout

[parthz-13]

Closes #2332

Summary

Adds a new two-cols-footer layout that complements the existing two-cols-header layout. This layout displays two columns with an optional top section and a footer section that spans both columns at the bottom.

Test Slide Screenshot

Implementation Details

• Follows the same pattern and conventions as two-cols-header.vue
• Uses CSS Grid with 3 rows: auto 1fr auto
• Maintains consistent prop structure (class, layoutClass)

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[parthz-13]

Hey @antfu ,
This PR is ready for review. Please let me know if there’s anything I should adjust or clarify.
Thanks!

[JPustkuchen]

Thanks @parthz-13! Looks great, but one change seems unrelated and should be removed, see comments.

[parthz-13]

Thanks @parthz-13! Looks great, but one change seems unrelated and should be removed, see comments.

Hey @JPustkuchen, thanks for catching that. It was an unintentional whitespace change. I’ve reverted it now.

[parthz-13]

hey @kermanx, just wanted to check if you had time to review this PR. Please let me know if there’s anything I should adjust or clarify.

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commit: e6ec750

[kermanx]

Why not use the bottom slot of two-cols-header?

---
layout: two-cols-header
---

This shows at the top, aligned to the start (top) of the grid

::left::
# Left
This shows on the left

::right::
# Right
This shows on the right

::bottom::
This spans both columns at the bottom (footer)

<style>
.two-cols-header {
  column-gap: 20px; /* Adjust the gap size as needed */
}
</style>