Initial public release

Aurum — a self-hosted personal finance operating system: cash flow,
net worth tracking, budgets, goals, recurring payments, reports,
proactive alerts, and a compound-interest returns calculator, all
bilingual (RU/EN) and mobile-first. Ships as a three-container Docker
Compose stack (Postgres + FastAPI + nginx-served React frontend).

See README.md for setup and CONTRIBUTING.md for development.

backend/app/models/budget.py

@@ -0,0 +1,22 @@
+"""A monthly spending limit for one expense category — compared against
+actual spend for whichever month is being viewed (services/budget_service.py).
+Not month-scoped itself: one limit per category, in effect until changed."""
+from decimal import Decimal
+
+from sqlalchemy import ForeignKey, Numeric
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db.base import Base
+from app.models.mixins import TimestampMixin
+
+
+class Budget(Base, TimestampMixin):
+    __tablename__ = "budgets"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    category_id: Mapped[int] = mapped_column(
+        ForeignKey("categories.id", ondelete="CASCADE"), nullable=False, unique=True
+    )
+    monthly_limit: Mapped[Decimal] = mapped_column(Numeric(14, 2), nullable=False)
+
+    category: Mapped["Category"] = relationship()