feat: add file name transformer for fenced code blocks (#535)

* feat: add file name transformer for fenced code blocks

* chore: update file names in fenced code blocks

src/utils/transformers/fileName.js

@@ -0,0 +1,39 @@
+export const transformerFileName = () => ({
+  pre(node) {
+    const raw = this.options.meta?.__raw?.split(" ");
+
+    if (!raw) return;
+
+    const metaMap = new Map();
+
+    for (const item of raw) {
+      const [key, value] = item.split("=");
+      metaMap.set(key, value.replace(/["'`]/g, ""));
+    }
+
+    const file = metaMap.get("file");
+
+    if (!file) return;
+
+    node.children.push({
+      type: "element",
+      tagName: "span",
+      properties: {
+        class: [
+          "px-2 py-1",
+          "absolute left-0 -top-6",
+          "rounded-t-md border border-b-0",
+          "bg-muted/50 text-foreground text-xs font-medium leading-4",
+        ],
+      },
+      children: [
+        {
+          type: "text",
+          value: file,
+        },
+      ],
+    });
+
+    this.addClassToHast(node, "mt-12 rounded-tl-none");
+  },
+});