CVE-2026-34978: reject ".." path traversal in the RSS notifier
notify-recipient-uri, both in notifier/rss.c and when the subscription
is created in the scheduler, and refuse to write when the target path
exists and is not a regular file; previously a remote IPP client could
make the lp-owned notifier clobber root-managed state such as
CacheDir/job.cache
CVE-2026-34979: fix heap buffer overflow when building filter option
strings; ipp_length() skipped NOVALUE, MIMETYPE, NAMELANG, TEXTLANG,
URI and URISCHEME attributes that get_options() does emit, so the
allocated options buffer was undersized