refactor: introduce app factory + blueprints (auth, core, admin users, invite); add utils and wsgi entrypoint; keep legacy routes for now

app/blueprints/auth.py

@@ -0,0 +1,29 @@
+from flask import Blueprint, render_template, request, redirect, url_for, flash
+from flask_login import login_user, logout_user
+from werkzeug.security import check_password_hash
+
+from app.models import User
+
+bp = Blueprint('auth', __name__)
+
+
+@bp.route('/login', methods=['GET', 'POST'], endpoint='login')
+def login():
+    if request.method == 'POST':
+        username = request.form['username']
+        password = request.form['password']
+        user = User.get_or_none(User.username == username)
+
+        if user and check_password_hash(user.password_hash, password):
+            login_user(user)
+            return redirect(url_for('dashboard' if not user.is_admin else 'manage_surveys'))
+        else:
+            flash('Неверный логин или пароль', 'danger')
+    return render_template('login.html', title='Вход')
+
+
+@bp.route('/logout', endpoint='logout')
+def logout():
+    logout_user()
+    return redirect(url_for('choose_survey'))
+