feat: render context-aware version dropdown (#235)

Switches version dropdown based on currently active docs.

## Demo


https://github.com/user-attachments/assets/acddcbad-6450-4038-92dd-0cf10b3e96b4

docusaurus.config.ts

@@ -184,11 +184,11 @@ const config: Config = {
           position: "right",
           docsPluginId: "default",
         },
-        // {
-        //   type: "docsVersionDropdown",
-        //   position: "right",
-        //   docsPluginId: "sdf",
-        // },
+        {
+          type: "docsVersionDropdown",
+          position: "right",
+          docsPluginId: "sdf",
+        },
         {
           type: "custom-Discord",
           position: "right",

src/theme/NavbarItem/DocsVersionDropdownNavbarItem.tsx

@@ -0,0 +1,22 @@
+import React from 'react';
+import {useActiveDocContext} from '@docusaurus/plugin-content-docs/client';
+import DocsVersionDropdownNavbarItem from '@theme-original/NavbarItem/DocsVersionDropdownNavbarItem';
+
+import type DocsVersionDropdownNavbarItemType from '@theme/NavbarItem/DocsVersionDropdownNavbarItem';
+import type {WrapperProps} from '@docusaurus/types';
+
+type Props = WrapperProps<typeof DocsVersionDropdownNavbarItemType>;
+
+export default function DocsVersionDropdownNavbarItemWrapper(props: Props): JSX.Element {
+  const activeDocContext = useActiveDocContext(props.docsPluginId);
+
+  if (!activeDocContext?.activeDoc) {
+    return null;
+  }
+
+  return (
+    <>
+      <DocsVersionDropdownNavbarItem {...props} />
+    </>
+  );
+}