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/market/__init__.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from app.config import Settings
+from app.market.base import MarketData
+from app.market.binance import BinanceMarketData
+from app.market.fake import FakeMarketData
+
+
+def build_market_data(settings: Settings) -> MarketData:
+    exchange = settings.exchange.lower()
+    if exchange in {"binance", "binanceus"}:
+        return BinanceMarketData()
+    raise ValueError(f"unsupported exchange: {settings.exchange}")
+
+
+__all__ = ["FakeMarketData", "MarketData", "build_market_data"]