feat(core,host): Wake-on-LAN sender + host MAC advertisement

Add a runtime-free Wake-on-LAN sender in punktfunk-core (per-interface subnet-directed broadcast + 255.255.255.255 on ports 9/7, repeated, optional last-known-IP unicast) exposed both as a Rust fn and a punktfunk_wake_on_lan C-ABI (ABI v3), plus a parse_mac helper. The host enumerates its wake-capable NIC MAC(s) and advertises them in a new mDNS `mac` TXT record (routed NIC first), and best-effort detects & warns (never modifies) when the NIC isn't armed for WoL.

MAC delivery is via the unauthenticated mDNS TXT rather than the connection handshake by design: a spoofed MAC only makes a wake fail (the packet is inert; the cert fingerprint still gates the connection), and it avoids threading through the hot connect path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/main.rs

@@ -22,6 +22,7 @@ mod audio;
 mod capture;
 mod config;
 mod discovery;
+mod wol;
 // Goal-1 stage 6: top-level platform-only modules live under `src/linux/` and `src/windows/`; `#[path]`
 // keeps the `crate::*` module names flat (every existing path is unchanged).
 #[cfg(target_os = "linux")]