Store live photos as their image and their video (closes #107)

A live photo, which Ente stores as one ZIP, is unpacked as it downloads
into its image and its video, each `<fileID>.<ext>` with its extension
from the ZIP, beside `<fileID>.livephoto.json`, which names the two.
Both are checked against the recorded hash and renamed into place only
when both are complete. A ZIP with a second image or video, or whose
parts come to more than 20 times its size plus 16 MiB, is refused. The
backup and the content cache count a live photo as stored only with both
files, album folders link both, `quak get` writes both, and the content
result gives the video as `videoPath`. A ZIP an earlier version stored
is replaced.

Model: opus-5-5

src/library/index.ts

@@ -397,7 +397,8 @@ export class Library {
                 originalsDays: opts.precacheOriginalsDays,
                 onEvent: opts.onProgress,
             });
-            precache.update(deriveRecordsFromStore(store));
+            const records = deriveRecordsFromStore(store);
+            precache.update(records);
             const extraPinned = opts.isOriginalPinned;
             cache = new ContentCache({
                 pools,
@@ -411,7 +412,12 @@ export class Library {
                     precache!.isPinned(fileID) ||
                     (extraPinned?.(fileID) ?? false),
             });
-            await cache.open();
+            // The records say at once which files are live photos, where
+            // `getFileByID` would search every file for each one cached.
+            await cache.open(
+                (fileID) =>
+                    records.photos.get(fileID)?.fileType === "livePhoto",
+            );
             precache.bind(cache);
         }