Add pipeline to publish playground

[nojaf]

[Copilot]

Pull request overview

This PR adds automated deployment of a tree-sitter playground to GitHub Pages and updates the tree-sitter CLI to a newer version to support the playground export functionality.

Changes:

• Updated tree-sitter-cli from version 0.25.2 to 0.26.3
• Added a GitHub Actions workflow to build and deploy the playground to GitHub Pages

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated no comments.

File	Description
package.json	Updated tree-sitter-cli dependency to version 0.26.3
package-lock.json	Updated lock file to reflect new tree-sitter-cli version with integrity hashes
.github/workflows/gh-pages.yml	New workflow that builds WASM, exports playground, and deploys to GitHub Pages

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