Align solid-markdown with react-markdown 10.1.0 and add Solid-native async rendering

[keithce]

Title

Align solid-markdown with react-markdown 10.1.0 and add Solid-native async rendering

Summary

This update moves solid-markdown from an older compatibility-focused API to an upstream-aligned react-markdown 10.1.0 style API, adapted for Solid. The rendering pipeline now follows the upstream remark -> rehype -> JSX runtime model, the public options match current upstream concepts, and async unified plugins are supported both on the server and on the client.

What changed

• Replaced the custom renderer/filter pipeline with an upstream-style processor flow and hast-util-to-jsx-runtime.
• Aligned the public API around Markdown, MarkdownAsync, MarkdownResource, remarkRehypeOptions, and urlTransform.
• Simplified custom component typing so overrides receive normal Solid intrinsic props plus node.
• Removed legacy wrapper-element behavior and made removed pre-v9 props fail explicitly at runtime instead of lingering as soft compatibility.
• Added a Solid-native client async path through MarkdownResource.
• Expanded SSR and client coverage to include rendering parity, URL safety, removed-prop runtime errors, plugin/property passthrough, and async lifecycle behavior.

Why this is valuable

• It makes the package easier to understand for anyone already using modern react-markdown.
• It removes older behavior that was diverging from upstream semantics and complicating maintenance.
• It gives Solid users a clear story for async plugins on both the server and the client.
• It tightens the package surface area and types instead of preserving multiple generations of API compatibility.
• It raises confidence in the port with a much broader regression suite across SSR and browser rendering.

Compatibility and migration

This change is intentionally breaking in the same places where upstream has already moved on:

• SolidMarkdown is removed in favor of the default Markdown export.
• Wrapper props such as class/className are removed; callers should wrap the component themselves.
• Legacy props such as source, plugins, renderers, allowNode, allowedTypes, disallowedTypes, transformLinkUri, and transformImageUri now throw.
• urlTransform replaces the older link/image transform props.
• renderingStrategy remains temporarily for the sync component only, but it is deprecated and intended for removal in the next major release.

Verification

Verified locally with:

pnpm lint
pnpm test
pnpm build

Current test coverage includes:

• SSR rendering coverage
• Browser rendering coverage
• URL sanitization and transform behavior
• Removed-prop runtime error coverage
• Async plugin behavior for both MarkdownAsync and MarkdownResource

Notes for review

• The goal here is not to preserve every historical solid-markdown API quirk. The goal is to make this package a clean Solid port of modern react-markdown.
• The only intentional short-term compatibility holdout is the deprecated renderingStrategy prop on Markdown.
• The README and demo docs were updated to describe the new API and the current verification story so users do not have to infer behavior from source alone.

[andi23rosca]

Thanks for this!

I'll have to play around with it and test it but I agree with the overall changes 👍🏻

[andi23rosca]

@keithce we should probably bump the version to 3.0.0 in the package.json since there's so many breaking changes in the API