⬆️ Upgrade frontend-tooling and docs

[aaronleopold]

This PR is primarily dev tooling updates, but it was a broad radius so am basing into experimental.

• Add lerna for better workspace management of frontend-specific packages
• Remove majority of cargo operations from otherwise frontend-specific files
  • I really want to start separating these for simplicity: cargo for rust, yarn/lerna for frontend
• Upgrade eslint and refactor configs accordingly
  • Fix all lints
• Fix tsc check scripts, I didn't configure it correctly for a monorepo with references
  • Fix all type errors
  • Add type checks to CI
• Upgrade next and nextra
• Touch up some of the docs, add SDK section 🙌

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Files with missing lines	Coverage Δ
core/src/lib.rs	0.00% <ø> (ø)