Add --ml and --exif flags to backup-metadata

--ml fetches face detections and CLIP embeddings from the /files/data/fetch
endpoint (type 'mldata'). Each blob is encrypted with the file's key and
gzipped; we decrypt with decryptBlob, gunzip, and include the parsed JSON
as 'mlData' in the per-file output. Fetched in batches of 200 file IDs.

--exif downloads each file, runs sharp().metadata() to extract image
properties (format, dimensions, color space, orientation), then parses
the raw EXIF buffer with exif-reader for structured tags (lens, ISO,
shutter, aperture, GPS altitude, etc.). Also captures raw IPTC, XMP,
and ICC profile data. Included as 'imageMetadata' in the per-file output.

Without either flag, behavior is unchanged (fast metadata-only dump).

Adds exif-reader 2.0.3 as a runtime dependency.
3 new tests (ML data decrypted, ML data absent when flag not set, EXIF
extraction). 119 total tests, all green.

bin/quak.ts

@@ -337,13 +337,25 @@ program
 program
     .command("backup-metadata")
     .description(
-        "Dump all decrypted account metadata (no file content) to a directory",
+        "Dump all decrypted account metadata to a directory of JSON files",
     )
     .argument("<dir>", "Output directory")
-    .action(async (dir: string) => {
+    .option(
+        "--ml",
+        "Include ML data (face detections, CLIP embeddings) from the Ente server",
+    )
+    .option(
+        "--exif",
+        "Download each file and extract full EXIF/IPTC/XMP metadata (slow)",
+    )
+    .action(async (dir: string, opts: { ml?: boolean; exif?: boolean }) => {
         await init();
         const client = requireSession();
-        await runMetadataBackup(client, dir, (msg) => stderr.write(msg + "\n"));
+        await runMetadataBackup(client, dir, {
+            mlData: opts.ml,
+            exif: opts.exif,
+            onProgress: (msg) => stderr.write(msg + "\n"),
+        });
     });
 
 program