Port to TypeScript & Playwright

[texodus]

This PR ports regular-table from JavaScript to TypeScript and migrates the test suite from Jest/Puppeteer to Playwright.

• The core library source files in src/js/ have been rewritten as TypeScript modules in src/ts/, adding type definitions for the virtual data model, scroll panel, table rendering, and event handling systems.
• Substantial rewrite of column resizing and rendering, which now use adoptedStyleSheets to apply updates in a batch rather than one-at-a-time.

Bonus:

• The test suite has been completely rewritten using playwright, with improved test coverage for features like addStyleListener, column resizing, scrolling behavior, and React integration.
• Example and feature files have been restructured from literate Markdown format into standalone JavaScript files with accompanying HTML and CSS, making them easier to run and maintain independently.