Use carbon-preprocess-svelte for faster, optimized builds

[metonym]

Review by commit.

Note: Git diff is massive since the lockfile has not been checked in to source control. Rebase on #235

This is optional, but I recommend incorporating the Carbon preprocessor for faster development/production builds and optimized CSS generation.

Svelte has first-class support for preprocessors. This means that code can be transformed before compilation.

carbon-preprocess-svelte automatically processes source code to rewrite Carbon imports to their optimized path, greatly reducing the number of initially loaded components.

# Carbon preprocessor automatically optimizes imports to avoid the barrel import penalty.
- import { Button } from "carbon-components-svelte";
+ import Button from "carbon-icons-svelte/src/Button/Button.svelte";

In the case of Carbon, I recommend the following:

• optimizeImports: automatically rewrites Carbon imports to the optimized path. Carbon has a lot of exports from its barrel file. Optimizing imports can greatly reduce cold start and build times, since it bypasses the barrel file.
• optimizeCss: Vite plugin that optimizes CSS from carbon-components-svelte at build time.

Results

Running locally on my machine, I observe ~1.21x (~17%) faster build times and ~45.8% reduced CSS output size (non-gzip).

npm run build

- ✓ 2204 modules transformed.
- ✓ built in 4.69s

+ ✓ 1970 modules transformed.
+ ✓ built in 3.86s

Optimized CSS

- .svelte-kit/output/client/_app/immutable/assets/0.BtlGoQkA.css    606.87 kB │ gzip:  55.92 kB
+ .svelte-kit/output/client/_app/immutable/assets/0.BtlGoQkA.css    328.90 kB │ gzip:  31.25 kB

[Luke-Roy-IBM]

lgtm

[Luke-Roy-IBM]

LGTM