feat: add momentum indicators and expand function coverage

Add a full Momentum Indicators category (momentum_indicators.go) with
26 new wrapped functions:

  ADX, ADXR, APO, AROON, AROONOSC, BOP, CCI, CMO, DX, IMI,
  MACD, MACDEXT, MACDFIX, MFI, MOM, MINUS_DI, MINUS_DM,
  PLUS_DI, PLUS_DM, PPO, ROC, ROCP, ROCR, ROCR100, RSI,
  STOCH, STOCHF, STOCHRSI, TRIX, ULTOSC, WILLR

- Register all new native symbols in Load() (loader.go)
- Declare corresponding native function variables in functions.go
- Add MAType enum (ta_ma_type.go) for MA-type parameters (SMA, EMA,
  WMA, DEMA, TEMA, TRIMA, KAMA, MAMA, T3)
- Add taResult constants (ta_result.go) mirroring TA-Lib return codes
- Each wrapper includes a doc comment with formula, interpretation, and
  known behavioral edge-case notes

README.md

@@ -23,6 +23,13 @@ This project currently exposes a small subset of TA-Lib functions:
 - Exponential/Logarithmic: `Exp`, `Ln`, `Log10`
 - Rounding: `Ceil`, `Floor`, `Sqrt`
 
+**Momentum Indicators**
+- Directional Movement: `ADX`, `ADXR`, `DX`, `MINUS_DI`, `MINUS_DM`, `PLUS_DI`, `PLUS_DM`
+- Oscillators: `APO`, `AROON`, `AROONOSC`, `BOP`, `CCI`, `CMO`, `IMI`, `MFI`, `MOM`, `PPO`, `RSI`, `TRIX`, `WILLR`, `ULTOSC`
+- Rate of Change: `ROC`, `ROCP`, `ROCR`, `ROCR100`
+- MACD family: `MACD`, `MACDEXT`, `MACDFIX`
+- Stochastic family: `STOCH`, `STOCHF`, `STOCHRSI`
+
 ## Requirements
 
 - Go `1.26`
@@ -107,6 +114,8 @@ func main() {
 
 - Indicator functions return `nil` when the underlying TA-Lib call fails.
 - Native TA-Lib functions are exposed with Go-style exported names such as `Add`, `Div`, `Max`, and `Sum`.
+- Functions accepting a moving-average type use the `MAType` constant (`SMA`, `EMA`, `WMA`, `DEMA`, `TEMA`, `TRIMA`, `KAMA`, `MAMA`, `T3`).
+- Functions returning two outputs (e.g. `AROON`, `MACD`, `STOCH`) return multiple slices; all are `nil` on failure.
 
 ## Project status