fix(mobile): English long-press action labels + clean thumb error placeholder

bug-report c25e9b55: long-press scene actions were in Polish — translate menu,
banner and confirm dialogs to English. Thumb 'error' state (e.g. expired sxyprn
thumbnail 404) now shows the same 🎬 placeholder as 'empty' instead of a ⚠ broken
glyph (bug 2026-06-10).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

mobile/src/SceneActionsContext.tsx

@@ -49,17 +49,17 @@ export function SceneActionsProvider({ children }: { children: React.ReactNode }
 
   const hide = React.useCallback(
     (scene: SceneOut) => {
-      Alert.alert('Ukryć scenę?', scene.title, [
-        { text: 'Anuluj', style: 'cancel' },
+      Alert.alert('Hide scene?', scene.title, [
+        { text: 'Cancel', style: 'cancel' },
         {
-          text: 'Ukryj',
+          text: 'Hide',
           style: 'destructive',
           onPress: async () => {
             try {
               await client.hideScene(scene.id);
               invalidate();
             } catch (e: any) {
-              Alert.alert('Nie udało się ukryć', e?.message || 'unknown error');
+              Alert.alert('Failed to hide', e?.message || 'unknown error');
             }
           },
         },
@@ -71,10 +71,10 @@ export function SceneActionsProvider({ children }: { children: React.ReactNode }
   const openActions = React.useCallback(
     (scene: SceneOut) => {
       if (pendingDuplicate) return; // w trakcie wyboru duplikatu — ignoruj
-      Alert.alert(scene.title, 'Akcje sceny', [
-        { text: 'Ukryj scenę', style: 'destructive', onPress: () => hide(scene) },
-        { text: 'Oznacz jako duplikat', onPress: () => setPending(scene) },
-        { text: 'Anuluj', style: 'cancel' },
+      Alert.alert(scene.title, 'Scene actions', [
+        { text: 'Hide scene', style: 'destructive', onPress: () => hide(scene) },
+        { text: 'Mark as duplicate', onPress: () => setPending(scene) },
+        { text: 'Cancel', style: 'cancel' },
       ]);
     },
     [pendingDuplicate, hide],
@@ -88,19 +88,19 @@ export function SceneActionsProvider({ children }: { children: React.ReactNode }
         return;
       }
       Alert.alert(
-        'Scalić duplikat?',
-        `„${dup.title}"\n\nscalić w\n\n„${target.title}"`,
+        'Merge duplicate?',
+        `"${dup.title}"\n\nmerge into\n\n"${target.title}"`,
         [
-          { text: 'Anuluj', style: 'cancel', onPress: () => setPending(null) },
+          { text: 'Cancel', style: 'cancel', onPress: () => setPending(null) },
           {
-            text: 'Scal',
+            text: 'Merge',
             onPress: async () => {
               try {
                 // keep = wybrany oryginał (target), drop = długo-naciśnięty duplikat (dup)
                 await client.mergeDuplicateScene(target.id, dup.id);
                 invalidate();
               } catch (e: any) {
-                Alert.alert('Scalanie nie powiodło się', e?.message || 'unknown error');
+                Alert.alert('Merge failed', e?.message || 'unknown error');
               } finally {
                 setPending(null);
               }
@@ -132,10 +132,10 @@ export function SceneActionsProvider({ children }: { children: React.ReactNode }
         <View style={styles.banner} pointerEvents="box-none">
           <View style={styles.bannerInner}>
             <Text style={styles.bannerText} numberOfLines={2}>
-              Wybierz oryginał — dotknij scenę, w którą scalić „{pendingDuplicate.title}"
+              Pick the original — tap the scene to merge "{pendingDuplicate.title}" into
             </Text>
             <Pressable onPress={cancelDuplicate} style={styles.bannerCancel} hitSlop={8}>
-              <Text style={styles.bannerCancelText}>Anuluj</Text>
+              <Text style={styles.bannerCancelText}>Cancel</Text>
             </Pressable>
           </View>
         </View>

mobile/src/components/Thumb.tsx

@@ -55,7 +55,9 @@ export function Thumb({ url, style, contentFit = 'cover', emptyGlyph = '🎬' }:
 
       {status === 'error' && (
         <View style={[StyleSheet.absoluteFill, styles.center]}>
-          <Text style={styles.glyphError}>⚠</Text>
+          {/* Błąd ładowania (np. wygasła sxyprn/trafficdeposit miniaturka, 404) →
+              czysty placeholder jak 'empty', nie alarmowe ⚠ (bug 2026-06-10). */}
+          <Text style={styles.glyph}>{emptyGlyph}</Text>
         </View>
       )}
     </View>