New filter rules no longer default to priority 100. Server picks
max(priority)+10 per account when client sends priority=None (or 10
if the account has no rules yet), and the UI pre-fills the input
with the next value instead of a fixed 100. Avoids ambiguous ordering
when multiple rules end up with the same priority.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>