build(pyproject.toml): add flask-socketio depedency

pyproject.toml

@@ -9,7 +9,11 @@ description = "The backbone of the remote PC fleet management system."
 readme = "README.md"
 authors = []
 requires-python = ">=3.13"
-dependencies = ["flask>=3.1.1", "flask-login>=0.6.3"]
+dependencies = [
+    "flask>=3.1.1",
+    "flask-login>=0.6.3",
+    "flask-socketio>=5.5.1",
+]
 license = { text = "GPL-3.0+" }
 
 [dependency-groups]