Wire image context menu into grid and gallery embeds

Thread onPreviewPress(index) through ImageLayoutGrid / GalleryItem and the
Gallery scroll item so multi-image embeds get the same iOS peek behaviour as
single-image embeds. Each grid cell wraps its Pressable in ImageContextMenu
with the image's true aspect ratio, so the preview lifts to the full
uncropped image even when the cell is cropped to square.

https://claude.ai/code/session_015REmux3R9uuEMMJUHxTyQT

src/components/Post/Embed/ImageContextMenu.tsx

@@ -1,4 +1,5 @@
 import {type ReactNode} from 'react'
+import {type StyleProp, type ViewStyle} from 'react-native'
 import {msg} from '@lingui/core/macro'
 import {useLingui} from '@lingui/react'
 
@@ -22,6 +23,7 @@ export function ImageContextMenu({
   aspectRatio,
   borderRadius,
   onPreviewPress,
+  style,
   children,
 }: {
   fullsizeUri: string
@@ -29,6 +31,7 @@ export function ImageContextMenu({
   aspectRatio: number | undefined
   borderRadius?: number
   onPreviewPress?: () => void
+  style?: StyleProp<ViewStyle>
   children: ReactNode
 }) {
   const {_} = useLingui()
@@ -46,7 +49,7 @@ export function ImageContextMenu({
   }
 
   return (
-    <ContextMenu.Root>
+    <ContextMenu.Root style={style}>
       <ContextMenu.Trigger
         preview={{
           type: 'image',

src/components/Post/Embed/ImageEmbed.tsx

@@ -57,6 +57,18 @@ export function ImageEmbed({
         )
       })
     }
+    const onPreviewPress = (index: number) =>
+      openLightbox({
+        images: items.map(item => ({
+          ...item,
+          thumbRect: null,
+          thumbRef: null,
+          thumbDimensions: null,
+          thumbBorderRadius: tokens.borderRadius.md,
+          type: 'image',
+        })),
+        index,
+      })
 
     if (images.length === 1) {
       const image = images[0]
@@ -70,19 +82,7 @@ export function ImageEmbed({
             fullsizeUri={image.fullsize}
             aspectRatio={aspect}
             borderRadius={tokens.borderRadius.md}
-            onPreviewPress={() =>
-              openLightbox({
-                images: items.map(item => ({
-                  ...item,
-                  thumbRect: null,
-                  thumbRef: null,
-                  thumbDimensions: null,
-                  thumbBorderRadius: tokens.borderRadius.md,
-                  type: 'image',
-                })),
-                index: 0,
-              })
-            }>
+            onPreviewPress={() => onPreviewPress(0)}>
             <AutoSizedImage
               crop={
                 rest.viewContext === PostEmbedViewContext.ThreadHighlighted
@@ -114,6 +114,7 @@ export function ImageEmbed({
             images={images}
             onPress={onPress}
             onPressIn={onPressIn}
+            onPreviewPress={onPreviewPress}
             viewContext={rest.viewContext}
           />
         </View>
@@ -126,6 +127,7 @@ export function ImageEmbed({
           images={images}
           onPress={onPress}
           onPressIn={onPressIn}
+          onPreviewPress={onPreviewPress}
           viewContext={rest.viewContext}
         />
       </View>