feat(523): restore reads the backup tar; python -m scribe.restore brings a fresh instance back

The restore route takes the tar as a raw body beside the JSON download.
scribe/restore.py reads either format, refuses a database that already
has an account (a restore re-creates everything with new ids, so into a
live instance it would duplicate rather than replace), has no size
limit, and says to restart so search indexes rebuild. An integration
test restores a written tar through the real restore_full_backup and
checks every id is remapped. docs/backups.md explains the file, why it
is uncompressed, both destinations, Fabled Archives as the worked
example, and restoring.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/scribe/routes/admin.py

@@ -59,7 +59,21 @@ async def backup():
 @admin_bp.route("/restore", methods=["POST"])
 @admin_required
 async def restore():
-    data = await request.get_json()
+    """Restore from an uploaded backup: the JSON download (application/json)
+    or the scheduled backup's tar (sent as the raw body). The upload is held
+    to the app's request-size limit; `python -m scribe.restore` has none, and
+    is the way in for a bigger file or a fresh instance."""
+    if request.mimetype == "application/json":
+        data = await request.get_json()
+    else:
+        import io
+
+        from scribe.services.backup_file import ArchiveError, read_archive
+
+        try:
+            data = read_archive(io.BytesIO(await request.get_data()))
+        except ArchiveError as exc:
+            return jsonify({"error": f"That file isn't a Scribe backup: {exc}"}), 400
     if not data:
         return jsonify({"error": "No backup data provided"}), 400