feat: enhance ui using javascript in admin area

- bundle js using parcel
- add markdown editor, html editor, dropdown and tooltip features using third-party packages
- integrate optimized inline svg icons from RemixIcon using svgo and a php helper
- add scripts in package.json to bundle icons, images, css and js
- update tailwind config to add purgecss lookups and typography plugin
- refactor views to add missing pages in user journey
- update admin's holy grail layout using css grid