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/engine/strategies/sma_cross.py

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+from __future__ import annotations
+
+from typing import ClassVar
+
+from app.engine.indicators import sma
+from app.engine.strategies.base import Strategy, StrategyContext, register
+from app.models import PositionSide
+
+
+@register
+class SmaCross(Strategy):
+    """Classic moving-average crossover, long-only."""
+
+    key: ClassVar[str] = "sma_cross"
+    name: ClassVar[str] = "SMA Crossover"
+    description: ClassVar[str] = (
+        "Open a long position when the fast SMA crosses above the slow SMA, "
+        "close it when the fast SMA crosses back below."
+    )
+    default_params: ClassVar[dict] = {"fast": 10, "slow": 30, "size": 1.0}
+    param_help: ClassVar[dict] = {
+        "fast": "Fast SMA period",
+        "slow": "Slow SMA period",
+        "size": "Fraction of equity to allocate per trade",
+    }
+    param_bounds: ClassVar[dict] = {"fast": (2, 200), "slow": (3, 400), "size": (0.01, 1.0)}
+
+    def on_candle(self, ctx: StrategyContext) -> None:
+        fast_period = int(self.params["fast"])
+        slow_period = int(self.params["slow"])
+        closes = ctx.closes
+        if len(closes) < slow_period + 2:
+            return
+
+        fast = sma(closes, fast_period)
+        slow = sma(closes, slow_period)
+        f_prev, f_now = fast[-2], fast[-1]
+        s_prev, s_now = slow[-2], slow[-1]
+        if None in (f_prev, f_now, s_prev, s_now):
+            return
+
+        crossed_up = f_prev <= s_prev and f_now > s_now
+        crossed_down = f_prev >= s_prev and f_now < s_now
+
+        if ctx.is_flat and crossed_up:
+            ctx.enter_long(size=float(self.params["size"]), reason="fast SMA crossed above slow")
+        elif ctx.side == PositionSide.LONG and crossed_down:
+            ctx.close(reason="fast SMA crossed below slow")