Optimistic Rollup of Fixes

[smorimoto]

This PR bundles various improvements and fixes accumulated across the project:

Configuration & Compatibility

• TypeScript 7 compatibility: Update documentation to reflect baseUrl deprecation, recommending paths instead across Ember, Nuxt, Remix, and Docusaurus configurations
• Major update to recommended.json: Modernise with current TypeScript best practices
• Remove baseUrl from configurations that included it (Nuxt, Remix, Docusaurus, Ember)

Tooling & Infrastructure

• GitHub Actions upgrades: Update to checkout@v6, setup-node@v6, and setup-deno@v2
• Test suite migration: Switch from pnpm to npm for simpler CI setup
• Deno modernisation: Add deno.json with JSR imports, update to Deno 2 APIs (Command API, JSONC parser)

Code Quality

• Add .editorconfig for consistent formatting across editors
• Standardise JSON formatting: Consistent array formatting, proper spacing, remove extraneous blank lines
• VS Code settings: Configure default formatters for JSON/JSONC and TypeScript files

Script Updates

• Migrate build scripts to modern Deno APIs
• Replace deprecated npm dependencies with JSR packages

All changes maintain backwards compatibility for end users, except recommended.json!

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Closes #324
Closes #323

[smorimoto]

@orta I sincerely apologise for the unusually large size of this pull request, but I would really appreciate it if you could review it. I am constantly helped by this repository, so I wanted to resolve all the problems in one go.