Markdown as its own plugin (hl:markdown): read, render and write Markdown

Markdown handling moves into one Hybriel plugin that every app uses, instead of copies in each app. Test: an app imports hl:markdown and shows a Markdown text; the same text comes back out unchanged after editing. Details:

• Creator: "makes sense to put the markdown in and out functionalities in its own plugin - routger needs it to render LLM responses in a chat".
• In: text → blocks (plain data). Render: a View component that shows the blocks safely (text nodes only, safe links). Out: blocks → Markdown text.
• Sources to merge: tickets.worldapi.org/markdown.hl + components/markdown.hl (base), gitoria.worldapi.org/markdown.hl (adds quotes, tables, rules), the parser/writer inside components.hybriel's md-editor.hl.
• For LLM answers: nested lists, code blocks with a language, tables, and text that is still arriving (an open code block must not break the page).
• First user: routger (/media/STORAGE/projects/routger on Loreana); later tickets, gitoria and the md-editor switch to it.