Initial commit: MyMidas personal finance tracker

Full-stack self-hosted finance app with FastAPI backend and React frontend.

Features:
- Accounts, transactions, budgets, investments with GBP base currency
- CSV import with auto-detection for 10 UK bank formats
- ML predictions: spending forecast, net worth projection, Monte Carlo
- 7 selectable themes (Obsidian, Arctic, Midnight, Vault, Terminal, Synthwave, Ledger)
- Receipt/document attachments on transactions (JPEG, PNG, WebP, PDF)
- AES-256-GCM field encryption, RS256 JWT, TOTP 2FA, RLS, audit log
- Encrypted nightly backups + key rotation script
- Mobile-responsive layout with bottom nav

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/db/models/budget.py

@@ -0,0 +1,30 @@
+import uuid
+from datetime import date, datetime
+from decimal import Decimal
+
+from sqlalchemy import Boolean, Date, DateTime, ForeignKey, Numeric, String, Text
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db.base import Base
+
+
+class Budget(Base):
+    __tablename__ = "budgets"
+
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    user_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
+    category_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), ForeignKey("categories.id"), nullable=False)
+    name: Mapped[str] = mapped_column(Text, nullable=False)
+    amount: Mapped[Decimal] = mapped_column(Numeric(20, 8), nullable=False)
+    currency: Mapped[str] = mapped_column(String(10), nullable=False)
+    period: Mapped[str] = mapped_column(String(20), nullable=False)  # weekly|monthly|quarterly|yearly
+    start_date: Mapped[date] = mapped_column(Date, nullable=False)
+    end_date: Mapped[date | None] = mapped_column(Date, nullable=True)
+    rollover: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    alert_threshold: Mapped[Decimal] = mapped_column(Numeric(5, 2), default=80, nullable=False)
+    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False, index=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+
+    category: Mapped["Category"] = relationship(back_populates="budgets", lazy="noload")  # type: ignore[name-defined]