feat: Allow configuring cache directory for @sveltejs/enhanced-img

[strfx]

This PR allows configuring the cache directory for @sveltejs/enhanced-img.

By default, processed images are cached in node_modules/.cache/imagetools. When running npm ci (e.g., in CI or on deployment), it completely wipes node_modules and thus the cache. Placing the cache outside of node_modules also allows caching processed images between CI runs.

Changes:

Add optional config object parameter to enhancedImages(). The object intentionally mirrors the cache options of imagetools to avoid coupling the two plugins. The parameter can be omitted to be backwards-compatible with any existing config.

Behavior:

imagetools's default cache options apply unless explicitly overwritten.

Example:

To place the caching directory to ./my-cache-dir, provide:

// vite.config.js
import { enhancedImages } from '@sveltejs/enhanced-img';

export default {
  plugins: [
    enhancedImages({
      cache: { directory: './my-cache-dir' }
    })
  ]
};

For a more detailed discussion, see #12615

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Latest commit: b96cdf4

The changes in this PR will be included in the next version bump.

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Name	Type
@sveltejs/enhanced-img	Minor

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[dominikg]

note i am not familiar with the cache impl of vite-imagetools

keeping a persistent cache across builds requires meticulous tracking of anything that could have an effect on the cache content. From dependency versions to configuration, code or asset changes. Otherwise stale cached output is going to lead to hard to track errors.

So is that cache really safe to store across builds or is it even flushed on buildStart and just there to avoid doing the same work twice during a single build?

[elliott-with-the-longest-name-on-github]

@dominikg it is a cache of processed images during build. It's stored in node_modules by default specifically because a lot of platforms cache that across builds.