docs: add More from Yako grid with animated previews

[yadaniyil]

Replaces the old "Check out other Yako packages" link list with a More from Yako grid: a small animated preview of each other Yako package, its name, and one line on what it does.

• Each tile is recorded from the package's real widget, so it shows exactly what the package does.
• The tiles live in yako-dev/.github. Updating a tile there updates it in every README.
• Each image has alt text that describes what the package does, for screen readers and for AI coding assistants reading the README.
• The grid sits between more-from-yako markers, so tools/more_from_yako.py in yako-dev/.github can update it later.

Docs only. pub.dev shows the new README after the next release.

🤖 Generated with Claude Code

[yadaniyil]

Merged. The tiles live in yako-dev/.github, so updating a tile there updates this grid too. pub.dev shows the grid after the next release.