Replace ipset+mangle approach with pure ip route tables.
Configuration via routes.d/ (IPv4) and routes6.d/ (IPv6) directories
where each subdirectory = gateway and .list symlinks = domain/IP lists.

Features:
- Hash-based change detection (skip if lists unchanged)
- Double check: file hash + resolved IPs diff
- Batch route loading via ip -batch
- Automatic cleanup of orphaned state
- --show/--force/--add/--del/--flush options

Also adds is_ipv6() and get_ipv6_list_bulk() to functions.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>