style: add image to figure plugin

- Improve styles for images, blockquotes, tables and more
- Fix unexpected line breaks

src/plugins/rehype-img-to-figure.mjs

@@ -0,0 +1,29 @@
+import { visit } from 'unist-util-visit'
+
+export function rehypeImgToFigure() {
+  return (tree) => {
+    visit(tree, 'element', (node) => {
+      if (
+        node.tagName === 'p'
+        && node.children
+        && node.children.length === 1
+        && node.children[0].tagName === 'img'
+        && node.children[0].properties.alt
+      ) {
+        const child = node.children[0]
+        const altText = child.properties.alt
+
+        node.tagName = 'figure'
+        node.children = [
+          child,
+          {
+            type: 'element',
+            tagName: 'figcaption',
+            properties: {},
+            children: [{ type: 'text', value: altText }],
+          },
+        ]
+      }
+    })
+  }
+}