feat: simplify journal connection via WebSocket upgrade

Refactor the journal server to run over WebSockets on the existing
HTTP server instead of a separate MQTT TCP port. This removes the need
for a separate port configuration and simplifies the connection flow
by auto-connecting to the current host.

- Remove `--mqtt-port` CLI option
- Attach Aedes broker to the HTTP server via WebSocket upgrade
- Update UI to remove manual broker URL and player name inputs
- Add "Content Source" access from the sidebar
- Update JournalPanel to auto-connect to the local server

src/cli/commands/serve.ts

@@ -210,7 +210,6 @@ export function createContentServer(
   port: number,
   distPath: string = distDir,
   host: string = "0.0.0.0",
-  mqttPort: number = 1883,
 ): ContentServer {
   let contentIndex: ContentIndex = {};
 
@@ -275,28 +274,24 @@ export function createContentServer(
   // ---- Journal / MQTT broker ----
   let journal: Awaited<ReturnType<typeof createJournalServer>> | null = null;
 
-  createJournalServer(contentDir, mqttPort).then((j) => {
-    journal = j;
-  });
-
-  // 创建请求处理器
+  // 创建 HTTP 服务器 BEFORE journal so we can pass it in
   const handleRequest = createRequestHandler(
     contentDir,
     distPath,
     () => contentIndex,
   );
-
-  // 创建 HTTP 服务器
   const server = createServer(handleRequest);
 
+  createJournalServer(contentDir, server).then((j) => {
+    journal = j;
+  });
+
   server.listen(port, host, () => {
     const displayHost = host === "0.0.0.0" ? "localhost" : host;
     console.log(`\n开发服务器已启动：http://${displayHost}:${port}`);
     console.log(`内容目录：${contentDir}`);
     console.log(`静态资源目录：${distPath}`);
-    console.log(
-      `MQTT 代理端口：${mqttPort} (connect via tcp://${displayHost}:${mqttPort})\n`,
-    );
+    console.log(`Journal 连接：ws://${displayHost}:${port}\n`);
   });
 
   return {
@@ -319,7 +314,6 @@ export const serveCommand: ServeCommandHandler = async (dir, options) => {
   const contentDir = resolve(dir);
   const port = parseInt(options.port, 10);
   const host = options.host || "0.0.0.0";
-  const mqttPort = parseInt(options.mqttPort || "1883", 10);
 
-  createContentServer(contentDir, port, distDir, host, mqttPort);
+  createContentServer(contentDir, port, distDir, host);
 };