idea: use yarn "zero installs" instead of ncc/bundler

[tmillr]

Pros

• No more build step (unless another compile-time tool such as Terser or TypeScript is introduced later on)
• All deps are committed and tracked in the repo
  • No need to run npm ci every time you test or switch a branch?
  • No need to worry about node_modules becoming out of sync when checking-out commits/branches
  • Better and more efficient than committing node_modules, although that's not being done currently anyway
• Experience using/understanding yarn cache

Cons

• Larger repo size (although e.g. git checkout action only clones a branch's HEAD commit by default instead of the entire history...assuming custom actions are cloned similarly? i.e. shallowly)
• Compatibility (especially dev deps, IDE tools/integration)
• More complicated usage/setup/config, more complicated than ncc and npm

Alternatively use pnpm for quicker and more efficient clean installs...still need bundler/ncc though, and pnpm has its own set of compat issues (although they can be worked-around).