added temp flask server and added flask to requirements

notebook/server.py

@@ -0,0 +1,7 @@
+from flask import Flask, jsonify
+
+app = Flask(__name__)
+
+@app.route('/')
+def index():
+    return jsonify({"message": "Thesis Notebook Server is running."})

pyproject.toml

@@ -39,6 +39,7 @@ dependencies = [
     "jupyterlab_server>=2.28.0,<3",
     "notebook_shim>=0.2,<0.3",
     "tornado>=6.2.0",
+    "flask>=3.1.2"
 ]
 dynamic = ["version"]