Keep leases alive during long restores and exports; PR review fixes

Full restore, raw directory restore, per-user export and the safety export
held a fixed-TTL lease on the location that nothing refreshed. A restore or
export running longer than that TTL let a cleanup take over and delete data
still in use. They now refresh the lease while they work (per blob, per row
batch, per written chunk), throttled to once a minute.

Also:
- backup:prune still applies snapshot retention when user-export retention
  fails for a location.
- The recovery kit carries the deletion delay, so a disaster recovery keeps
  the original protection instead of falling back to 7 days. Older kits
  still import with the default.
- CI checkouts no longer persist the token in the git config.
- recoveryKit() has its real return type; the stale baseline entry is gone.

lib/Service/LeaseService.php

@@ -76,6 +76,17 @@ final class LeaseService {
 		$qb->executeStatement();
 	}
 
+	/** Wraps $refresh so calling it often (per file, per row batch) only touches the database every $seconds. */
+	public static function throttled(callable $refresh, int $seconds = 60): \Closure {
+		$last = time();
+		return static function () use ($refresh, $seconds, &$last): void {
+			if (time() - $last >= $seconds) {
+				$refresh();
+				$last = time();
+			}
+		};
+	}
+
 	/** Run $fn under a lease; $refresh() can be called during long work. */
 	public function with(string $name, string $mode, int $ttl, callable $fn): mixed {
 		$id = $this->acquire($name, $mode, $ttl);