fix: no upscaling, EXIF rotation, content cache key, encoder tuning

[lxsmnsyc]

Summary

Stops the plugin from enlarging images, turns photos upright, and makes the
build cache hit in CI. Also tunes the encoders, keeps animated WebP frames, and
fixes the dev server default for publicPath.

Changes

• Images are never enlarged. Sizes wider than the source are dropped and the
  source width is used instead, so srcset only lists real widths.
• The img fallback source uses the largest real width, not the largest
  configured size.
• Photos are turned upright using their EXIF orientation. The reported width and
  height match how the photo displays, so the aspect ratio box is correct.
• The inline preview is turned upright too.
• Animated images keep every frame when the output is WebP. AVIF, JPEG and PNG
  keep the first frame. With animation turned on, sharp stacks every frame into
  one tall image in those formats.
• JPEG uses mozjpeg and is smaller at the same quality. WebP uses its highest
  effort.
• PNG is compressed harder and stays lossless. The quality option never
  applied to PNG, and the README now says so.
• The cache key hashes the file content instead of the modification time. A
  fresh checkout gives every file a new time, so the cache never hit in CI.
• The cache key leaves out the file path, which also differs between checkouts.
• publicPath defaults to Vite's publicDir. The old default of dist is not
  served by the dev server, so images 404ed unless publicPath was set.
• Every img carries its intrinsic width and height.
• The noscript image uses loading="lazy", so readers with no JavaScript do
  not download every image at once.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@solidjs/image@7

commit: 3b27cb3