feat: Add @observablehq/notebook-kit support

[GordonSmith]

Checklist:

• The commit message is properly formatted and free of typos.
  • The commit message title makes sense in a changelog, by itself.
  • The commit message includes a "fixes" reference if appropriate.
  • The commit is signed.
• The change has been fully tested:
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Testing:

[GordonSmith]

@jeclrsg ready for review...

[Copilot]

Pull Request Overview

This PR adds support for @observablehq/notebook-kit integration to the observablehq-compiler package. It introduces new compilation pathways and utilities to work with the notebook-kit runtime system.

Key changes:

• Adds @observablehq/notebook-kit as a dependency and integrates its runtime capabilities
• Implements new compiler functions to support notebook-kit format alongside existing Observable formats
• Adds comprehensive test coverage with sample HTML notebooks demonstrating the new functionality

Reviewed Changes

Copilot reviewed 15 out of 16 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
vite.config.ts	Configures build system with npm/jsr import resolution and top-level await support
tests/index-notebookkit.ts	Adds comprehensive test suite for notebook-kit integration with HTML, OMD, and OJS formats
src/util.ts	Extends utilities with notebook-kit conversion functions and function constructor improvements
src/compiler.ts	Adds compileKit function and overloaded compile methods for notebook-kit support
src/index.ts	Exports new notebook-kit related functions
package.json	Adds notebook-kit and related dependencies

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[GordonSmith]

...rebased and passing tests....

[jeclrsg]

@GordonSmith only thing I wanted to double-check about was that case in vite.config.ts for jquery ui. Would approve otherwise.