chore(repo): use tsup (again) to produce compatible esm and cjs builds

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Component / Package Name:

This PR contains:

• [x] bugfix
• [ ] feature
• [ ] refactor
• [ ] documentation
• [ ] other

Are tests included?

• [ ] yes (bugfixes and features will not be merged without tests)
• [x] no

Breaking Changes?

• [ ] yes (breaking changes will not be merged unless absolutely necessary)
• [x] no

If yes, please include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.

List any relevant issue numbers:

Fixes #38

Description

This PR (re)introduces tsup for building packages. We're taking a page out of tanstack's book for how they're using tsup. Used https://stackblitz.com/edit/stackblitz-starters-jkyxrt?file=package.json,index.js to test this with a test release of the font component, and tested manually, locally. Shouldn't result in any disruptions for anyone using the packages already.

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The interdependency between all in the templates that render is using in tests is forcing us to publish these updates manually, locally rather than using CI.