Add kv.list() pagination playground example

[tmchow]

Summary

Added an interactive playground example for puter.kv.list() that shows cursor-based pagination in action. Also updated the docs to wire the existing pagination code snippet to the playground.

Changes

New file: src/docs/src/playground/examples/kv-list.html

• Creates 6 sample key-value pairs
• Paginates through them 2 at a time using cursor-based pagination
• Shows each page with keys and values
• Cleans up sample data at the end

Updated: src/docs/src/KV/list.md

• Changed the pagination example code fence from html (static snippet) to html;kv-list (playground-linked), matching the pattern used by other examples in the docs

Testing

The example follows the same pattern as existing playground examples (kv-incr.html, kv-del.html, etc.) and uses the documented puter.kv.list() API with limit and cursor options.

Fixes #2755

This contribution was developed with AI assistance (Claude Code).

[reynaldichernando]

hi @tmchow thank you for the changes,
i've left some review on your PR
also, make sure to add the new example in the examples.js entry (you can find other docs for this)

[tmchow]

Fixed in the latest push:

• Restored the inline code example in list.md
• Reverted kv-list.html to the original basic list example
• Created a new kv-list-pagination.html for the cursor/limit playground demo
• Registered the new example in examples.js

[reynaldichernando]

thank you for the updates!
i've made minor changes to improve readability, but this is already lookin good

[tmchow]

Thanks for the review and merge, @reynaldichernando.