Bitcoin favicon, more strategies, default timeframe 5m

- Add an SVG Bitcoin favicon and link it in index.html.
- New indicators: macd() and roc().
- Five new strategies: macd_trend, bollinger_reversion, donchian_breakout,
  ema_cross, momentum (plus the existing sma_cross, rsi_reversion).
- Default TIMEFRAME is now 5m (config, .env.example, compose, workflow, UI).

backend/tests/test_indicators.py

@@ -2,7 +2,7 @@ from __future__ import annotations
 
 import pytest
 
-from app.engine.indicators import atr, ema, rolling_std, rsi, sma
+from app.engine.indicators import atr, ema, macd, roc, rolling_std, rsi, sma
 from app.schemas import Candle
 
 
@@ -38,3 +38,25 @@ def test_atr_flat_market_is_zero() -> None:
 def test_rolling_std() -> None:
     result = rolling_std([1, 1, 1, 1], 2)
     assert result[-1] == pytest.approx(0.0)
+
+
+def test_roc() -> None:
+    values = [100.0, 110.0, 121.0, 100.0]
+    out = roc(values, 2)
+    assert out[0] is None and out[1] is None
+    assert out[2] == pytest.approx(0.21)
+    assert out[3] == pytest.approx(-0.09090909, rel=1e-4)
+
+
+def test_macd_shapes_and_crossover_sign() -> None:
+    rising = [float(i) for i in range(1, 80)]
+    macd_line, signal_line, histogram = macd(rising, 12, 26, 9)
+    assert len(macd_line) == len(rising)
+    assert macd_line[-1] is not None and signal_line[-1] is not None
+    # In a steady uptrend MACD is positive (but can be below its signal after lag).
+    assert macd_line[-1] > 0
+    assert histogram[-1] == pytest.approx(macd_line[-1] - signal_line[-1])
+
+    falling = [float(i) for i in range(80, 0, -1)]
+    macd_falling, _, _ = macd(falling, 12, 26, 9)
+    assert macd_falling[-1] < 0