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

package.json

@@ -52,6 +52,7 @@
     "solid-js": "^1.9.3",
     "three": "^0.183.2",
     "three-3mf-exporter": "^45.1.0",
+    "ws": "^8.21.0",
     "yarn-spinner-loader": "^0.1.0",
     "zod": "^4.4.3"
   },
@@ -66,6 +67,7 @@
     "@types/jest": "^30.0.0",
     "@types/js-yaml": "^4.0.9",
     "@types/node": "^22.19.13",
+    "@types/ws": "^8.18.1",
     "husky": "^9.1.7",
     "jest": "^29.7.0",
     "jest-environment-jsdom": "^29.7.0",