mobile: skeleton grid while scene lists load (perceived perf)

Scene-list screens showed a small spinner while waiting on the API, so a slow
list read felt like a blank stall. Replace the initial-load spinner on
ScenesScreen and TagScenesScreen with a SceneGridSkeleton — a 2-col grid of
pulsing placeholder tiles laid out 1:1 with SceneTile (16:9 thumb + title + meta
lines). It paints instantly with zero data, so the screen feels responsive even
when the query takes a moment, and the skeleton->content swap doesn't reflow.

Pairs with the backend list-count fix (most filtered lists are now ~0.1s); the
skeleton also masks the residual slow path (enormous tags) so it no longer reads
as a freeze.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

mobile/src/components/SceneGridSkeleton.tsx

@@ -0,0 +1,81 @@
+/**
+ * SceneGridSkeleton — placeholder grid pokazywany podczas ŁADOWANIA listy scen,
+ * zamiast spinnera. Rysuje się natychmiast (zero danych), więc ekran "ożywa" w ms
+ * nawet gdy backend liczy kilka sekund — percepcyjna szybkość jak w dużych apkach
+ * (YT/Netflix pokazują szkielety/placeholdery zanim dane dojdą).
+ *
+ * Layout 1:1 z SceneTile (2-col, thumb 16:9 + linia tytułu + linia meta), żeby
+ * przejście skeleton→content nie "skakało". Subtelny pulse (Animated opacity loop),
+ * bez zewnętrznych zależności.
+ */
+import React from 'react';
+import { Animated, StyleSheet, View } from 'react-native';
+
+import { theme } from '../theme';
+
+function usepulse() {
+  const v = React.useRef(new Animated.Value(0.4)).current;
+  React.useEffect(() => {
+    const loop = Animated.loop(
+      Animated.sequence([
+        Animated.timing(v, { toValue: 0.85, duration: 700, useNativeDriver: true }),
+        Animated.timing(v, { toValue: 0.4, duration: 700, useNativeDriver: true }),
+      ]),
+    );
+    loop.start();
+    return () => loop.stop();
+  }, [v]);
+  return v;
+}
+
+function SkeletonTile({ opacity }: { opacity: Animated.Value }) {
+  return (
+    <View style={styles.tile}>
+      <Animated.View style={[styles.thumb, { opacity }]} />
+      <Animated.View style={[styles.lineTitle, { opacity }]} />
+      <Animated.View style={[styles.lineMeta, { opacity }]} />
+    </View>
+  );
+}
+
+/** `count` kafelków (parzysta liczba dla 2-col siatki). */
+export function SceneGridSkeleton({ count = 8 }: { count?: number }) {
+  const opacity = usepulse();
+  const rows = Math.ceil(count / 2);
+  return (
+    <View style={styles.grid} pointerEvents="none">
+      {Array.from({ length: rows }).map((_, r) => (
+        <View key={r} style={styles.row}>
+          <SkeletonTile opacity={opacity} />
+          <SkeletonTile opacity={opacity} />
+        </View>
+      ))}
+    </View>
+  );
+}
+
+const styles = StyleSheet.create({
+  grid: { marginTop: 2 },
+  row: { flexDirection: 'row', gap: 10, marginBottom: 14 },
+  tile: { flex: 1 },
+  thumb: {
+    width: '100%',
+    aspectRatio: 16 / 9,
+    borderRadius: 6,
+    backgroundColor: theme.bgElevated,
+  },
+  lineTitle: {
+    height: 12,
+    borderRadius: 4,
+    backgroundColor: theme.bgElevated,
+    marginTop: 8,
+    width: '85%',
+  },
+  lineMeta: {
+    height: 9,
+    borderRadius: 4,
+    backgroundColor: theme.bgElevated,
+    marginTop: 6,
+    width: '55%',
+  },
+});

mobile/src/screens/ScenesScreen.tsx

@@ -15,6 +15,7 @@ import {
 import { Image } from 'expo-image';
 import * as Haptics from 'expo-haptics';
 import { SceneTile } from '../components/SceneTile';
+import { SceneGridSkeleton } from '../components/SceneGridSkeleton';
 import { Thumb } from '../components/Thumb';
 import { useClient } from '../ClientContext';
 import { theme } from '../theme';
@@ -119,9 +120,11 @@ export function ScenesScreen() {
         <FavoritesButton />
       </View>
 
-      {isLoading && <ActivityIndicator color={theme.fg} />}
       {error instanceof Error && <Text style={styles.error}>{error.message}</Text>}
 
+      {isLoading ? (
+        <SceneGridSkeleton count={8} />
+      ) : (
       <FlatList
         data={items}
         keyExtractor={(s) => s.id}
@@ -145,6 +148,7 @@ export function ScenesScreen() {
         ListEmptyComponent={!isLoading ? <Text style={styles.muted}>no scenes</Text> : null}
         contentContainerStyle={{ paddingBottom: 24 }}
       />
+      )}
 
       <ScenesFilterModal
         visible={filterOpen}

mobile/src/screens/TagScenesScreen.tsx

@@ -4,7 +4,6 @@ import type { NativeStackNavigationProp } from '@react-navigation/native-stack';
 import { useQuery } from '@tanstack/react-query';
 import React from 'react';
 import {
-  ActivityIndicator,
   FlatList,
   Pressable,
   StyleSheet,
@@ -12,6 +11,7 @@ import {
   View,
 } from 'react-native';
 import { SceneTile } from '../components/SceneTile';
+import { SceneGridSkeleton } from '../components/SceneGridSkeleton';
 import { useClient } from '../ClientContext';
 import type { RootStackParamList } from '../navigation';
 import { theme } from '../theme';
@@ -41,9 +41,11 @@ export function TagScenesScreen() {
 
   return (
     <View style={styles.container}>
-      {isLoading && <ActivityIndicator color={theme.fg} />}
       {error instanceof Error && <Text style={styles.error}>{error.message}</Text>}
 
+      {isLoading ? (
+        <SceneGridSkeleton count={10} />
+      ) : (
       <FlatList
         data={data?.items ?? []}
         keyExtractor={(s) => s.id}
@@ -62,6 +64,7 @@ export function TagScenesScreen() {
         ListEmptyComponent={!isLoading ? <Text style={styles.muted}>no scenes</Text> : null}
         contentContainerStyle={{ paddingBottom: 24 }}
       />
+      )}
     </View>
   );
 }