v2.2.0 — chart() with TradingView Lightweight Charts

feat: v2.1.0 — BB, ATR, StochRSI, OBV, VWAP

- Add Bollinger Bands (.bb), ATR (.atr), Stochastic RSI (.stochRSI),
  OBV (.obv), and VWAP (.vwap) indicators
- Add TalaChain methods for all five new indicators
- Fix getStochRSI negative index bug (Math.max guard on tail-fill loop)
- Update README, CHANGELOG, docs site for v2.1.0
- Add unit tests for all five new indicators