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/currency.py

@@ -0,0 +1,31 @@
+import uuid
+from datetime import datetime
+from decimal import Decimal
+
+from sqlalchemy import Boolean, DateTime, Integer, Numeric, String, Text
+from sqlalchemy.dialects.postgresql import UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db.base import Base
+
+
+class Currency(Base):
+    __tablename__ = "currencies"
+
+    code: Mapped[str] = mapped_column(String(10), primary_key=True)
+    name: Mapped[str] = mapped_column(Text, nullable=False)
+    symbol: Mapped[str] = mapped_column(String(5), nullable=False)
+    is_crypto: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    decimal_places: Mapped[int] = mapped_column(Integer, default=2, nullable=False)
+    is_active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
+
+
+class ExchangeRate(Base):
+    __tablename__ = "exchange_rates"
+
+    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    base_currency: Mapped[str] = mapped_column(String(10), nullable=False, index=True)
+    quote_currency: Mapped[str] = mapped_column(String(10), nullable=False, index=True)
+    rate: Mapped[Decimal] = mapped_column(Numeric(20, 10), nullable=False)
+    source: Mapped[str] = mapped_column(String(50), nullable=False)
+    fetched_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, index=True)