Feat: Add script to apply subscriptions

src/meal_manager/models.py

@@ -1,5 +1,5 @@
 import typing
-from datetime import datetime
+from datetime import date, datetime
 
 from sqlalchemy import ForeignKey
 from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column, relationship
@@ -153,3 +153,15 @@ class Subscription(Base):
             return ", ".join(result)
         else:
             return "Alle"
+
+    def valid_on(self, date: date) -> bool:
+        weekday = date.weekday()
+        return {
+            0: self.monday,
+            1: self.tuesday,
+            2: self.wednesday,
+            3: self.thursday,
+            4: self.friday,
+            5: self.saturday,
+            6: self.sunday,
+        }[weekday]