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/app/engine/indicators.py

@@ -113,6 +113,44 @@ def rolling_std(values: Sequence[float], period: int) -> list[Number]:
     return out
 
 
+def macd(
+    values: Sequence[float],
+    fast: int = 12,
+    slow: int = 26,
+    signal: int = 9,
+) -> tuple[list[Number], list[Number], list[Number]]:
+    """Return (macd line, signal line, histogram), each aligned with ``values``."""
+    ema_fast = ema(values, fast)
+    ema_slow = ema(values, slow)
+    macd_line: list[Number] = [
+        (f - s) if f is not None and s is not None else None
+        for f, s in zip(ema_fast, ema_slow, strict=True)
+    ]
+    signal_line: list[Number] = [None] * len(values)
+    start = next((i for i, value in enumerate(macd_line) if value is not None), None)
+    if start is not None:
+        valid = [value for value in macd_line[start:] if value is not None]
+        for offset, value in enumerate(ema(valid, signal)):
+            signal_line[start + offset] = value
+    histogram: list[Number] = [
+        (m - s) if m is not None and s is not None else None
+        for m, s in zip(macd_line, signal_line, strict=True)
+    ]
+    return macd_line, signal_line, histogram
+
+
+def roc(values: Sequence[float], period: int = 10) -> list[Number]:
+    """Rate of change over ``period`` bars, as a fraction (0.02 = +2%)."""
+    if period <= 0:
+        raise ValueError("period must be positive")
+    out: list[Number] = [None] * len(values)
+    for i in range(period, len(values)):
+        previous = values[i - period]
+        if previous:
+            out[i] = (values[i] - previous) / previous
+    return out
+
+
 def last(series: Sequence[Number]) -> Number:
     for value in reversed(series):
         if value is not None: