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).

frontend/src/components/StrategyForm.vue

@@ -8,7 +8,7 @@ const props = defineProps({
   submitLabel: { type: String, default: 'Run' },
   submitClass: { type: String, default: 'btn-primary' },
   symbol: { type: String, default: 'BTC/USDT' },
-  timeframe: { type: String, default: '1m' },
+  timeframe: { type: String, default: '5m' },
   presets: { type: Array, default: () => [] },
 })
 const emit = defineEmits(['submit', 'save-preset', 'delete-preset', 'load-preset'])