dashboard: show LAN status in Local Services panel header

- Add lan_enabled to ServerCtx
- Add lan field to /stats API (enabled, peer count)
- Dashboard shows "LAN off" (dim) or "LAN on · N peers" (green)
- Tooltip shows enable command or mDNS service type

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main.rs

@@ -159,6 +159,7 @@ async fn main() -> numa::Result<()> {
             format!(".{}", config.proxy.tld)
         },
         proxy_tld: config.proxy.tld.clone(),
+        lan_enabled: config.lan.enabled,
     });
 
     let zone_count: usize = ctx.zone_map.values().map(|m| m.len()).sum();