Add meal v2 flow and user timezone support

Introduces a new add_meal_v2 blueprint with barcode scanning, item search, and improved meal logging UI. Adds user timezone support: login form now captures timezone, User model and database schema updated, and timezone is set on login. Refactors templates and forms to support these changes, and removes the old login template.

application/utils.py

@@ -1,6 +1,7 @@
 from flask_login import current_user
 from flask import redirect, url_for, flash
 from typing import Optional
+from zoneinfo import ZoneInfo
 
 
 def login_required():
@@ -19,3 +20,12 @@ def default_return(next_page: Optional[str] = None):
     if current_user.is_admin:
         return redirect(url_for("admin.food_items"))
     return redirect(url_for("dashboard"))
+
+
+def is_valid_timezone(tz: str) -> bool:
+    try:
+        ZoneInfo(tz)
+    except Exception:
+        print(Exception)
+        return False
+    return True