Add category_budget satellite table for time-bounded per-category budgets

src/models/__init__.py

@@ -1,5 +1,6 @@
 from src.models.b4w import B4wExport as B4wExport
 from src.models.b4w import Category as Category
+from src.models.category_budget import CategoryBudgetDb as CategoryBudgetDb
 from src.models.comdirect import ComdirectCreditCard as ComdirectCreditCard
 from src.models.comdirect import ComdirectDepot as ComdirectDepot
 from src.models.comdirect import ComdirectGiro as ComdirectGiro

src/models/b4w.py

@@ -135,6 +135,7 @@ class CategoryDb(BaseModelDb):
         "CategoryDb", remote_side="CategoryDb.id", back_populates="children"
     )
     children = relationship("CategoryDb", back_populates="parent")
+    budgets = relationship("CategoryBudgetDb", back_populates="category")
 
 
 class B4wDb(IngestdbBase):

src/models/category_budget.py

@@ -0,0 +1,27 @@
+from datetime import date
+from decimal import Decimal
+
+from sqlalchemy import Date, ForeignKey, Numeric
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from src.models._common import BaseModelDb
+
+
+class CategoryBudgetDb(BaseModelDb):
+    """Budget amount for a category, optionally bounded to a time window.
+
+    Satellite table to ``category``: one category may have several budgets
+    (e.g. one per month). ``valid_from``/``valid_to`` are nullable; ``None``
+    means unbounded on that side.
+    """
+
+    __tablename__ = "category_budget"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    category_id: Mapped[int] = mapped_column(ForeignKey("category.id"), nullable=False)
+    amount_eur: Mapped[Decimal] = mapped_column(Numeric(12, 2), nullable=False)
+    valid_from: Mapped[date | None] = mapped_column(Date, nullable=True, default=None)
+    valid_to: Mapped[date | None] = mapped_column(Date, nullable=True, default=None)
+
+    # relationship
+    category = relationship("CategoryDb", back_populates="budgets")