update docs

docs/architecture.md

@@ -59,8 +59,8 @@ infrastructure.
 | Logging | Log4j2 + `log4j-slf4j2-impl` | 2.26.0 |
 | Testing | JUnit Jupiter 6 + Mockito 5 | — |
 
-The HTTP **server** for the internal API uses the JDK built-in
-`com.sun.net.httpserver.HttpServer` (no external framework); see [web-api.md](web-api.md).
+The HTTP **server** for the internal API uses embedded Javalin (with OpenAPI/Swagger plugins); see
+[web-api.md](web-api.md).
 
 ## Startup lifecycle
 
@@ -157,5 +157,4 @@ block the others. Effectively this means:
 | `…http`                                           | Internal web API and HTTP client module                                                                 |
 | `…music`                                          | Music domain (service, manager, queue, scheduler, track loading)                                        |
 | `…utils`                                          | `Settings` / `SettingsProvider`, `ChannelMessagePurger`, `MusicUtils`                                   |
-| `…shared.util`                                    | Cross-cutting helpers                                                                                   |
 | `…exceptions`                                     | Custom exception hierarchy                                                                              |