feat(binding): add `::include` component for rendering markdown from a string

[miguelrk]

Problem

{{ data.content }} interpolates a string as escaped text. It does not call parseMarkdown.

CMS / DB templates often store a markdown string and need it parsed and rendered at render time:

::include{:value="data.content"}
::

Today each host must register its own component. That repeats the same pattern in HTML, Vue, React, Svelte, Angular, ANSI, etc.

Alternatively, we could have a three-bracket syntax: {{{ data.content }}} to render as markdown? That would be more ergonomic.

Proposal

Add an ::include (or ::embed/::render/::content/::md/::markdown/::fragment? But include seems to be more aligned to industry standards) binding component next to If and For:

• Resolve value from Binding scope (data. / props. / …)
• Call parseMarkdown on the string (same plugins as the parent parse, or a documented subset)
• Map the resulting nodes with the current renderer and scope
• Empty / non-string → render nothing

Same registration model as If / For: opt-in via Binding components, not a new parse-time syntax.

Happy to open a PR once the name and plugin-inheritance rules are agreed.

[xMrAfonso]

Sounds like this could potentially also simply be a settings that could be enabled on the comark component itself? Just my thoughts.