v0.1.0

Added

• nyat run — single TCP/UDP mapping task with STUN discovery
• nyat batch — run multiple mapping tasks from a TOML config file
• Exec hook (-e / exec) — run a command on mapping change via environment variables
• IPv4/IPv6 preference for DNS resolution
• Linux: interface binding (-i), fwmark (-f), force SO_REUSEPORT (--force-reuse)
• nyat-core library crate with async builder API