Date a Photo's save path by the membership its record is read from

A Photo kept the first membership of its file, while its record (and so
takenAt and year) comes from the most recently synced one. The record
projection now keeps that same membership for the Photo, so savePath
and isLocal carry the date of takenAt. A test covers one file in two
albums whose edited times differ.

Model: opus-5-5

test/library/content-library.test.ts

@@ -416,6 +416,50 @@ describe("Photo save path, local copy, content and EXIF", () => {
         await lib.close();
     });
 
+    it("dates the save path by the membership its takenAt comes from", async () => {
+        // One file in two albums. The date edited in Ente has reached album 2's
+        // copy, synced later, but album 1 still has an earlier edit.
+        const older = file(1, 1);
+        older.pubMagicMetadata = {
+            editedTime: new Date(2026, 1, 1, 12).getTime() * 1000,
+        };
+        const newer = file(1, 2);
+        newer.updationTime = 2;
+        newer.pubMagicMetadata = {
+            editedTime: new Date(2026, 3, 15, 12).getTime() * 1000,
+        };
+        const client = {
+            whoami: () => ({ email: "u@example.com", userID: USER_ID }),
+            collectionsSince: async (): Promise<CollectionsPage> => ({
+                collections: [collection(1), collection(2)],
+                deleted: [],
+                cursor: 1,
+            }),
+            filesSince: async (args: {
+                collectionID: number;
+            }): Promise<FilesPage> => ({
+                files: [args.collectionID === 1 ? older : newer],
+                deleted: [],
+                cursor: 1,
+            }),
+        };
+        const lib = await open({ client });
+        const photo = lib.photos.byID({ fileID: 1 })!;
+
+        expect(photo.takenAt).toBe(new Date(2026, 3, 15, 12).getTime());
+        expect(photo.savePath).toBe(
+            join(
+                root,
+                "backup",
+                "2026",
+                "2026-04",
+                "2026-04-15",
+                "2026-04-15.1.jpg",
+            ),
+        );
+        await lib.close();
+    });
+
     it("has a save path, and is not local, without a content source", async () => {
         const lib = await open({ contentSource: undefined });
         const photo = lib.photos.byID({ fileID: 1 })!;