chore: add rehypeUnwrapImg plugin for image processing optimization, update katex resource path

src/plugins/rehype-unwrap-img.mjs

@@ -0,0 +1,23 @@
+import { visit } from 'unist-util-visit'
+
+export function rehypeUnwrapImg() {
+  return (tree) => {
+    visit(tree, 'element', (node, index, parent) => {
+      if (
+        node.tagName === 'p'
+        && node.children
+        && parent
+        && node.children.every(child =>
+          child.tagName === 'img'
+          || (child.type === 'text' && child.value.trim() === ''),
+        )
+      ) {
+
+        const imgNodes = node.children.filter(child => child.tagName === 'img')
+        if (imgNodes.length > 0) {
+          parent.children.splice(index, 1, ...imgNodes)
+        }
+      }
+    })
+  }
+}