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/index.ts

@@ -17,7 +17,6 @@ program
   .description("运行一个 web 服务器预览目录中的内容，并实时监听更新")
   .argument("[dir]", "要预览的目录", ".")
   .option("-p, --port <port>", "HTTP 端口号", "3000")
-  .option("--mqtt-port <port>", "MQTT 代理端口号", "1883")
   .option("-h, --host <host>", "主机地址", "0.0.0.0")
   .action(serveCommand);