feat: update gallery state to require item, itemCreatedAt, and itemPosition; modify related functions to utilize new properties

__generated__/lexicons.ts

···
       },
       galleryState: {
         type: 'object',
+        required: ['item', 'itemCreatedAt', 'itemPosition'],
         description:
           "Metadata about the photo's relationship with the subject content. Only has meaningful content when photo is attached to a gallery.",
         properties: {
           item: {
             type: 'string',
             format: 'at-uri',
+          },
+          itemCreatedAt: {
+            type: 'string',
+            format: 'datetime',
+          },
+          itemPosition: {
+            type: 'integer',
           },
         },
       },

__generated__/types/social/grain/photo/defs.ts

···
 /** Metadata about the photo's relationship with the subject content. Only has meaningful content when photo is attached to a gallery. */
 export interface GalleryState {
   $type?: 'social.grain.photo.defs#galleryState'
-  item?: string
+  item: string
+  itemCreatedAt: string
+  itemPosition: number
 }
 
 const hashGalleryState = 'galleryState'

lexicons/social/grain/photo/defs.json

···
     },
     "galleryState": {
       "type": "object",
+      "required": ["item", "itemCreatedAt", "itemPosition"],
       "description": "Metadata about the photo's relationship with the subject content. Only has meaningful content when photo is attached to a gallery.",
       "properties": {
-        "item": { "type": "string", "format": "at-uri" }
+        "item": { "type": "string", "format": "at-uri" },
+        "itemCreatedAt": { "type": "string", "format": "datetime" },
+        "itemPosition": { "type": "integer" }
       }
     }
   }

src/lib/gallery.ts

···
 import { photoToView } from "./photo.ts";
 
 type PhotoWithMeta = WithBffMeta<Photo> & {
-  galleryItemUri?: string;
+  item?: WithBffMeta<GalleryItem>;
   exif?: WithBffMeta<PhotoExif>;
 };
 
···
       // Attach the galleryItem uri as itemUri
       galleryPhotosMap.get(galleryUri)?.push({
         ...photo,
-        galleryItemUri: item.uri,
+        item,
       });
     }
   }
···
     },
 ): Un$Typed<PhotoView> | undefined {
   if (isPhoto(item)) {
-    return photoToView(did, item, item.exif, item.galleryItemUri);
+    return photoToView(did, item, item.exif, item.item);
   }
   return undefined;
 }

src/lib/photo.ts

···
   did: string,
   photo: WithBffMeta<Photo>,
   exif?: WithBffMeta<PhotoExif>,
-  galleryItemUri?: string,
+  item?: WithBffMeta<GalleryItem>,
 ): $Typed<PhotoView> {
   return {
     $type: "social.grain.photo.defs#photoView",
···
     alt: photo.alt,
     aspectRatio: photo.aspectRatio,
     exif: exif ? exifToView(exif) : undefined,
-    gallery: galleryItemUri ? { item: galleryItemUri } : undefined,
+    gallery: item
+      ? {
+        item: item.uri,
+        itemPosition: item.position,
+        itemCreatedAt: item.createdAt,
+      }
+      : undefined,
   };
 }