quak backup writes the account and album records backup-metadata writes (closes #166)

quak backup now writes account.json with the account's email and user ID,
adds each album's ownerID, isShared, updationTime and, when present, its
magicMetadata, pubMagicMetadata and sharedMagicMetadata to the album's
JSON, and adds updationTime to each file's JSON. The fields and their order
match backup-metadata's account.json, _collection.json and per-file JSON.
The interface runBackup drives gains whoami, which the library passes
through from its client.

Model: opus-5-5
Co-authored-by: clawbot <sneak+clawbot@sneak.cloud>

TODO.md

@@ -25,6 +25,12 @@ declares one.
 
 # Completed Steps
 
+- 2026-10-06: `quak backup` writes the account and album records
+  `backup-metadata` writes (issue 166): `account.json` with the account's
+  `email` and `userID`, and in each album's JSON its `ownerID`, `isShared`,
+  `updationTime` and, when present, its three layers of magic metadata. Each
+  file's JSON gains its `updationTime`.
+
 - 2026-10-05: `quak backup` writes each file's ML data (its faces and CLIP
   embedding) into the file's JSON as `mlData`, the payload
   `lib.mldata.forFile()` returns (issue 163). `lib.backup()` waits for an ML