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/index.html

@@ -3,6 +3,9 @@
   <head>
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <link rel="apple-touch-icon" href="/favicon.svg" />
+    <meta name="theme-color" content="#F7931A" />
     <title>Crypto Trader</title>
   </head>
   <body class="bg-surface text-slate-100">

frontend/public/favicon.svg

@@ -0,0 +1,9 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" width="32" height="32">
+  <circle cx="16" cy="16" r="16" fill="#F7931A"/>
+  <text x="16" y="23.5" text-anchor="middle" font-family="Arial, Helvetica, sans-serif"
+        font-size="21" font-weight="bold" fill="#ffffff">B</text>
+  <rect x="13.9" y="4.2" width="2.2" height="4.6" rx="1.1" fill="#ffffff"/>
+  <rect x="17.6" y="4.2" width="2.2" height="4.6" rx="1.1" fill="#ffffff"/>
+  <rect x="13.9" y="23.2" width="2.2" height="4.6" rx="1.1" fill="#ffffff"/>
+  <rect x="17.6" y="23.2" width="2.2" height="4.6" rx="1.1" fill="#ffffff"/>
+</svg>

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'])