Used corepack to install the latest pnpm, and regenerated the lock file.
Removed the npm lock file. Husky v4 was not playing nicely with the
latest pnpm, so I updated husky to the latest version and moved the
pre-commit hook to .husky/pre-commit as v9 expects.

* Using plugins for esbuild:
    - esbuild-plugin-copy
    - esbuild-sass-plugin
    - custom plugin to run tsc
* Upgraded concurrently and nodemon to latest versions.
* Updated package.json dev script:
    - use pnpm
    - nodemon: only watch build dir and config
    - use --raw to get colors
* Don't serve 'assets' path (it no longer exists).
* Streamline html.ts route and use new build paths. Only need to import
  one css file as it is being bundled.
* Update other middleware to use new paths