feat: use custom type to handle existing naive datetimes

app/portal/bridge.py

@@ -1,6 +1,7 @@
 from typing import Optional
 
-from flask import render_template, Response, flash, redirect, url_for, Blueprint
+from flask import (Blueprint, Response, flash, redirect, render_template,
+                   url_for)
 from flask.typing import ResponseReturnValue
 
 from app.extensions import db