feat: 15 funciones finance — indicadores, riesgo e IO de mercado

11 funciones puras con implementación real:
SMA, EMA, RSI, BollingerBands, VWAP, LogReturn, AnnualizedVolatility,
SharpeRatio, MaxDrawdown, NormalizeOHLCV, TickToOHLCV

4 funciones impuras (stubs):
FetchOHLCV, StreamTicks, WriteOHLCVToParquet, LoadOHLCVFromDuckDB

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

functions/finance/tick_to_ohlcv.md

@@ -0,0 +1,37 @@
+---
+name: tick_to_ohlcv
+kind: function
+lang: go
+domain: finance
+version: "1.0.0"
+purity: pure
+signature: "func TickToOHLCV(prices, volumes []float64, timestamps []int64, intervalSecs int64) (open, high, low, close, vol []float64)"
+description: "Agrega datos de ticks en velas OHLCV segun un intervalo de tiempo en segundos."
+tags: [finance, ohlcv, aggregate, tick]
+uses_functions: []
+uses_types: [tick_go_finance, ohlcv_go_finance]
+returns: [ohlcv_go_finance]
+returns_optional: false
+error_type: ""
+imports: []
+tested: false
+tests: []
+test_file_path: ""
+file_path: "functions/finance/tick_to_ohlcv.go"
+---
+
+# tick_to_ohlcv
+
+Agrega ticks (precio, volumen, timestamp) en velas OHLCV. Los ticks se agrupan en buckets de `intervalSecs` segundos. Los timestamps deben estar en unix seconds y ordenados cronologicamente.
+
+## Ejemplo
+
+```go
+o, h, l, c, v := finance.TickToOHLCV(
+    []float64{100, 101, 99, 102},
+    []float64{10, 20, 15, 25},
+    []int64{1000, 1005, 1055, 1060},
+    60,
+)
+// Genera 2 velas: [1000-1059] y [1060-1119]
+```