Crypto trading bot: engine, brokers, backtester, dashboard, deploy

FastAPI backend with a single-strategy async engine, paper and Binance
brokers, pure-python indicators, a backtester that shares the engine's
portfolio math, and a Vue dashboard with a live WebSocket feed. Adds the
Gitea Actions CI/CD workflow that deploys to Traefik via docker_default.

backend/app/db.py

@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+from collections.abc import Iterator
+
+from sqlalchemy import create_engine
+from sqlalchemy.orm import Session, sessionmaker
+
+from app.config import REPO_ROOT, get_settings
+from app.models import Base
+
+_settings = get_settings()
+
+
+def _normalize_url(url: str) -> tuple[str, dict]:
+    connect_args: dict = {}
+    if url.startswith("sqlite"):
+        prefix, _, path = url.partition("sqlite:///")
+        if path and not path.startswith("/"):
+            url = f"{prefix}sqlite:///{REPO_ROOT / path}"
+        connect_args = {"check_same_thread": False}
+    return url, connect_args
+
+
+_url, _connect_args = _normalize_url(_settings.database_url)
+engine = create_engine(_url, connect_args=_connect_args, pool_pre_ping=True)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)
+
+
+def init_db() -> None:
+    Base.metadata.create_all(bind=engine)
+
+
+def get_session() -> Iterator[Session]:
+    session = SessionLocal()
+    try:
+        yield session
+    finally:
+        session.close()