feature: support Astro transformer

[jlarmstrongiv]

Implementation examples:

• See ipx Feature Request: Support for Self Hosted image manipulation server (Thumbor, Imgproxy, Imaginary) #37 (comment)
• ipx PR https://github.com/ascorbic/unpic/pull/85/files
• ipx demo PR chore: fixes to ipx demo #87
• imagekit https://github.com/ascorbic/unpic/pull/91/files

Astro image

• Documentation https://docs.astro.build/en/guides/images/
• Custom image component https://docs.astro.build/en/recipes/build-custom-img-component/
• Image service API https://docs.astro.build/en/reference/image-service-reference/
• Image endpoint https://github.com/withastro/astro/blob/main/packages/astro/src/assets/endpoint/generic.ts
• Required options https://github.com/withastro/astro/blob/0ab6bad7dffd413c975ab00e545f8bc150f6a92f/packages/astro/src/assets/services/service.ts#L124

Example

• URL
  • /_image?href=https%3A%2F%2Fmedia.npr.org%2Fassets%2Fimg%2F2017%2F06%2F03%2Fgettyimages-453879976-59801bc8f1f6bda5175c3098bb0d9a28696394be.jpg&w=1915&f=webp
  • /_image?href=%2F%40fs%2FUsers%2Fuser%2FDesktop%2Fprojects%2Fastro-unpic%2Fpublic%2Fblog-placeholder-about.jpg%3ForigWidth%3D960%26origHeight%3D480%26origFormat%3Djpg&w=480&f=avif
• Parameters
  • href
  • w (width)
  • h (height)
  • f (format)
  • q (quality, number | "low" | "mid" | "high" | "max")
    • https://github.com/withastro/astro/blob/44bfc9bbba5cecda0bd70e02069eeaecf8bca911/packages/astro/src/assets/services/sharp.ts#L13C1-L18
    • https://github.com/withastro/astro/blob/44bfc9bbba5cecda0bd70e02069eeaecf8bca911/packages/astro/src/assets/services/squoosh.ts#L14-L30
  • origWidth
  • origHeight
  • origFormat

I will work on a PR to support the Astro _image endpoint with unpic. Astro supports many of the frontend frameworks that unpic supports, so making them work together would be a win-win