fix(downloads): refresh BaseItemDto for Chapters before queuing offline

Some screens fetch items with a fields filter (e.g. series detail uses
["MediaSources", "MediaStreams", "Overview", "Trickplay"]) and pass the
resulting DTO straight into the download flow. Jellyfin only returns
Chapters in that case when explicitly listed, so the snapshot we store
under DownloadedItem.item carries Chapters: undefined and the offline
player renders no ticks / list / current-chapter label.

initiateDownload now re-fetches the item via getUserLibraryApi.getItem
(no fields filter -> full DTO incl. Chapters) when Chapters is missing,
and uses the enriched item for both getDownloadUrl and the snapshot. If
the refresh call fails we log and fall back to the original item — the
download itself still proceeds.

Trickplay offline already worked (useTrickplay reads trickPlayData.path
from the downloaded sheets).

components/DownloadItem.tsx

@@ -9,6 +9,7 @@ import type {
   BaseItemDto,
   MediaSourceInfo,
 } from "@jellyfin/sdk/lib/generated-client/models";
+import { getUserLibraryApi } from "@jellyfin/sdk/lib/utils/api/user-library-api";
 import { type Href } from "expo-router";
 import { t } from "i18next";
 import { useAtom } from "jotai";
@@ -195,9 +196,30 @@ export const DownloadItems: React.FC<DownloadProps> = ({
         );
       }
       const downloadDetailsPromises = items.map(async (item) => {
+        // Ensure the snapshot we store offline carries the Chapters array.
+        // Page-level fetches sometimes use a fields filter that omits it; the
+        // offline player would then render no chapter ticks / list.
+        let itemForDownload = item;
+        if (!itemForDownload.Chapters && itemForDownload.Id) {
+          try {
+            const enriched = await getUserLibraryApi(api).getItem({
+              itemId: itemForDownload.Id,
+              userId: user.Id!,
+            });
+            if (enriched.data) {
+              itemForDownload = enriched.data;
+            }
+          } catch (e) {
+            console.warn(
+              "[DownloadItem] failed to refresh item for Chapters, falling back to original",
+              e,
+            );
+          }
+        }
+
         const { mediaSource, audioIndex, subtitleIndex } =
           itemsNotDownloaded.length > 1
-            ? getDefaultPlaySettings(item, settings!)
+            ? getDefaultPlaySettings(itemForDownload, settings!)
             : {
                 mediaSource: selectedOptions?.mediaSource,
                 audioIndex: selectedOptions?.audioIndex,
@@ -206,7 +228,7 @@ export const DownloadItems: React.FC<DownloadProps> = ({
 
         const downloadDetails = await getDownloadUrl({
           api,
-          item,
+          item: itemForDownload,
           userId: user.Id!,
           mediaSource: mediaSource!,
           audioStreamIndex: audioIndex ?? -1,
@@ -218,7 +240,7 @@ export const DownloadItems: React.FC<DownloadProps> = ({
 
         return {
           url: downloadDetails?.url,
-          item,
+          item: itemForDownload,
           mediaSource: downloadDetails?.mediaSource,
         };
       });