simplify: unify route structs, fix prefix collision, lint fixes

- Unify RouteConfig/RouteEntry/RouteResponse into single RouteEntry
- Fix prefix collision: /api no longer matches /apiary (segment boundary check)
- Add path traversal rejection in route API
- Extract MdnsAnnouncement struct (clippy type_complexity)
- cargo fmt

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

src/main.rs

@@ -217,7 +217,11 @@ async fn main() -> numa::Result<()> {
     let proxy_bind: std::net::Ipv4Addr = if config.lan.enabled {
         std::net::Ipv4Addr::UNSPECIFIED
     } else {
-        config.proxy.bind_addr.parse().unwrap_or(std::net::Ipv4Addr::LOCALHOST)
+        config
+            .proxy
+            .bind_addr
+            .parse()
+            .unwrap_or(std::net::Ipv4Addr::LOCALHOST)
     };
 
     // Spawn HTTP reverse proxy for .numa domains