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).

.env.example

@@ -16,7 +16,7 @@ DATABASE_URL=sqlite:///./data/trader.db
 MODE=paper
 EXCHANGE=binance
 SYMBOL=BTC/USDT
-TIMEFRAME=1m
+TIMEFRAME=5m
 # How often the engine polls for new candles, in seconds
 POLL_INTERVAL=5
 # Candles fetched per tick and kept for indicators