fix(chapters): address review findings + trickplay polish

Copilot + CodeRabbit review findings:
- React.memo ChapterTicks and ChapterList (project guideline: hot-path
  components must use React.memo to cut redraw work during control
  updates).
- chapterNameAt now sorts the chapter array once instead of twice per
  call. The previous version went through currentChapterIndex
  (chapterStartsMs + sort) then sortedChapters (sort again). Runs on
  every playback tick, so the duplicate work added up.
- Import getUserLibraryApi from the public barrel
  (@jellyfin/sdk/lib/utils/api) instead of the deep internal path
  (@jellyfin/sdk/lib/utils/api/user-library-api) to match the rest of
  the codebase and avoid coupling to SDK file layout.

TrickplayBubble polish:
- Sit just above the slider (bottom: 0) so the bubble no longer overlaps
  the progress bar.
- Move the chapter-name + timestamp overlay to the bottom-left of the
  preview frame, smaller font, in front of the surrounding overlays
  (zIndex + elevation).

BottomControls cleanup:
- Drop dev-only "pick one to test" comment in favour of a one-line note
  on TICK_HEIGHT.
- Inline scrubMs into its useMemo callback so the scrub-chapter-name
  lookup only recomputes while a slide is active.

components/DownloadItem.tsx

@@ -9,7 +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 { getUserLibraryApi } from "@jellyfin/sdk/lib/utils/api";
 import { type Href } from "expo-router";
 import { t } from "i18next";
 import { useAtom } from "jotai";

components/chapters/ChapterList.tsx

@@ -6,7 +6,7 @@
 
 import { Ionicons } from "@expo/vector-icons";
 import type { ChapterInfo } from "@jellyfin/sdk/lib/generated-client/models";
-import { useEffect, useMemo, useRef } from "react";
+import { memo, useEffect, useMemo, useRef } from "react";
 import { useTranslation } from "react-i18next";
 import { FlatList, Modal, Pressable, StyleSheet, View } from "react-native";
 import { Text } from "@/components/common/Text";
@@ -30,7 +30,7 @@ interface ChapterListProps {
 
 const ROW_HEIGHT = 48;
 
-export function ChapterList({
+function ChapterListComponent({
   visible,
   chapters,
   currentPositionMs,
@@ -151,6 +151,8 @@ export function ChapterList({
   );
 }
 
+export const ChapterList = memo(ChapterListComponent);
+
 const styles = StyleSheet.create({
   backdrop: {
     flex: 1,

components/chapters/ChapterTicks.tsx

@@ -4,7 +4,7 @@
  * so the slider underneath still receives touches.
  */
 
-import { useState } from "react";
+import { memo, useState } from "react";
 import { type LayoutChangeEvent, PixelRatio, View } from "react-native";
 import type { ChapterMarker } from "@/utils/chapters";
 
@@ -19,7 +19,7 @@ interface ChapterTicksProps {
   width?: number;
 }
 
-export function ChapterTicks({
+function ChapterTicksComponent({
   markers,
   // Semi-transparent black contrasts against both the filled progress
   // (#fff) and the unfilled track (rgba(255,255,255,0.2)) so the ticks
@@ -83,3 +83,5 @@ export function ChapterTicks({
     </View>
   );
 }
+
+export const ChapterTicks = memo(ChapterTicksComponent);

components/video-player/controls/BottomControls.tsx

@@ -189,7 +189,6 @@ export const BottomControls: FC<BottomControlsProps> = ({
               onPress={() => setChapterListVisible(true)}
               hitSlop={10}
               className='justify-center mr-4'
-              style={{ marginTop: 10 }}
               accessibilityRole='button'
               accessibilityLabel={t("chapters.open")}
             >

components/video-player/controls/TrickplayBubble.tsx

@@ -52,8 +52,9 @@ export const TrickplayBubble: FC<TrickplayBubbleProps> = ({
       style={{
         position: "absolute",
         left: -62,
-        // Drop the bubble closer to the slider — less floating-high feel.
-        bottom: -20,
+        // Sit just above the slider — high enough not to overlap the
+        // progress bar, low enough to feel anchored to the thumb.
+        bottom: 0,
         paddingTop: 12,
         paddingBottom: 5,
         width: tileWidth * 1.5,

utils/chapters.ts

@@ -70,9 +70,16 @@ export const chapterNameAt = (
   positionMs: number,
   chapters: ChapterInfo[] | null | undefined,
 ): string | null => {
-  const idx = currentChapterIndex(positionMs, chapters);
-  if (idx < 0) return null;
+  // Sort once, derive both the active index and the entry from the same array
+  // — `chapterNameAt` runs on every playback tick, so paying for one `sort()`
+  // instead of two is worth the duplication of the index loop here.
   const sorted = sortedChapters(chapters);
+  let idx = -1;
+  for (let i = 0; i < sorted.length; i++) {
+    if (positionMs >= sorted[i].positionMs) idx = i;
+    else break;
+  }
+  if (idx < 0) return null;
   const name = sorted[idx]?.chapter.Name;
   return name && name.length > 0 ? name : null;
 };