feat: add mobile sidebar

app/books/bg/[chapter]/[verse]/page.tsx

@@ -3,6 +3,7 @@ import { PageHeader } from "@/components/page-header";
 import { notFound } from "next/navigation";
 import { getBookMeta, getSingleVerse, getChapterVerseIndex } from "@/lib/api";
 import { ChapterViewer } from "@/app/books/chapter-viewer";
+import type { MobileNavGroup } from "@/components/mobile-nav";
 
 type BgMeta = {
   book: string;
@@ -42,6 +43,19 @@ export default async function VersePage({
   );
   if (!verse) notFound();
 
+  // Build mobile nav groups — single flat list of chapters
+  const mobileNavGroups: MobileNavGroup[] = [
+    {
+      title: "Chapters",
+      items: bgMeta.chapters.map((ch) => ({
+        slug: `${ch.number}`,
+        label: `${ch.number}. ${ch.title}`,
+        href: `/books/bg/${ch.number}/1`,
+        type: "chapter",
+      })),
+    },
+  ];
+
   return (
     <div className="min-h-screen bg-background">
       <PageHeader sticky wide>
@@ -70,6 +84,8 @@ export default async function VersePage({
           chapter={parseInt(chapter)}
           basePath={`/books/bg/${chapter}`}
           showBengali={false}
+          mobileNavGroups={mobileNavGroups}
+          mobileNavBookTitle="Bhagavad-gītā As It Is"
         />
       </div>
     </div>