feat: pwa functionality

app.py

@@ -1,6 +1,6 @@
 import os
 from dotenv import load_dotenv
-from flask import Flask, render_template, redirect, url_for, request, flash
+from flask import Flask, render_template, redirect, url_for, request, flash, send_from_directory
 from flask_sqlalchemy import SQLAlchemy
 from flask_login import (
     LoginManager,
@@ -58,7 +58,11 @@ class MealPlan(db.Model):
 def load_user(user_id):
     return User.query.get(int(user_id))
 
+# PWA service worker
 
+@app.route('/sw.js')
+def serve_sw():
+    return send_from_directory('static', 'sw.js', mimetype='application/javascript')
 
 @app.route("/")
 def index():