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/base.py

@@ -0,0 +1,28 @@
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+from sqlalchemy.orm import DeclarativeBase
+
+from app.config import get_settings
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+def create_engine():
+    settings = get_settings()
+    return create_async_engine(
+        settings.database_url,
+        pool_size=10,
+        max_overflow=20,
+        pool_pre_ping=True,
+        echo=settings.is_development,
+    )
+
+
+def create_session_factory(engine):
+    return async_sessionmaker(
+        engine,
+        class_=AsyncSession,
+        expire_on_commit=False,
+        autoflush=False,
+    )