Live photo download no longer removes what was at its destination

The image and video are renamed into place, and the rename already
replaces the image's name, so the removal and the test that planted a
ZIP there are gone, along with the comments describing it.

Adds a test for a live photo the content cache recorded with no video,
because it opened before knowing the file is a live photo while no JSON
file named its image and video: original() fetches both again and writes
the JSON file. The comment on that check now names this case.

Model: opus-5-5

test/library/content.test.ts

@@ -596,6 +596,36 @@ describe("ContentCache live photos", () => {
         expect(second!.pathsFor(5)).toEqual({});
     });
 
+    it("fetches a live photo's image and video again when the cache opened before knowing it is a live photo and no JSON file names them", async () => {
+        const { file: live, body } = await asLivePhoto(file(5, "IMG_5.HEIC"));
+        mkdirSync(originals(), { recursive: true });
+        writeFileSync(join(originals(), "5.heic"), "an image");
+        writeFileSync(join(originals(), "5.mov"), "a video");
+        const cache = cacheOf([live], new Map([[5, body]]));
+        // Opened without being told that file 5 is a live photo, the cache
+        // records one of the two files as its original, with no video.
+        await cache.open();
+
+        const events: string[] = [];
+        const result = await cache.original(5, {
+            onProgress: (e) => events.push(e.status),
+        });
+
+        expect(events.at(-1)).toBe("done");
+        expect(result).toEqual({
+            path: join(originals(), "5.heic"),
+            videoPath: join(originals(), "5.mov"),
+            bytes: IMAGE.length,
+        });
+        expect(readFileSync(result.path)).toEqual(Buffer.from(IMAGE));
+        expect(readFileSync(result.videoPath!)).toEqual(Buffer.from(VIDEO));
+        expect(
+            JSON.parse(
+                readFileSync(join(originals(), "5.livephoto.json"), "utf-8"),
+            ),
+        ).toEqual({ image: "5.heic", video: "5.mov" });
+    });
+
     it.each(["missing", "empty"])(
         "fetches a live photo again when the video its JSON file names is %s",
         async (state) => {