switch to flask_login, finish login implementation, add basic home page

app/routes/auth.py

@@ -1,7 +1,10 @@
 from flask import Blueprint, render_template, request, redirect, url_for, session, flash
+from flask_login import login_user
 from app.db import get_db
 from werkzeug.security import generate_password_hash, check_password_hash
 
+from app.models.user import User
+
 auth_bp = Blueprint("auth", __name__)
 
 @auth_bp.route("/login", methods=["GET", "POST"])
@@ -11,11 +14,16 @@ def login():
         password = request.form["password"]
 
         db = get_db()
-        user = db.execute("SELECT * FROM users WHERE username = ?", (username,)).fetchone()
+        row = db.execute(
+            "SELECT * FROM users WHERE username = ?",
+            (username,)
+        ).fetchone()
 
-        if user and check_password_hash(user["password"], password):
-            session["user_id"] = user["id"]
-            return redirect(url_for("main.main"))
+        if row and check_password_hash(row["password"], password):
+            user = User(id=row["id"], username=row["username"])
+            login_user(user)
+
+            return redirect(url_for("main.home"))
         else:
             flash("Invalid username or password")