MDX Callout and Code Components

Specify a small MDX component map: a callout, a code block with a title, and a link that refuses javascript: URLs. STACK [NEXT.JS MDX | ASTRO MDX | CONTENTLAYER] Authors are: [STAFF | ALSO OUTSIDE CONTRIBUTORS] DELIVER 1) The component signatures and the markdown the author writes. Keep the author syntax boring. 2) The callout kinds: note, warning. Not twelve colors. The warning is not only color; it has a text label. 3) The link component: allow http, https, and relative URLs; reject javascript and data URLs if contributors are not fully trusted. Show the check. 4) Code blocks: a title prop, overflow scroll, and no client-side highlighter on every page if a build-time one exists. Say which we use. 5) How unknown components fail the build rather than rendering a mystery tag. Do not allow raw HTML from outside contributors unless I said we trust them, and if I did, say what we still strip (script, iframe).