v0.1.0 of drafter_finance_engine

Pure, UI-free engine for Drafter Finance trading charts — scales, viewport math, indicators, hit-testing and a platform-agnostic display list. No Flutter. Changelog excerpt: Initial release — the pure-Dart engine behind drafter_finance. - Technical indicators: SMA, EMA, RSI, MACD, Bollinger Bands. - Linear scales, padded value ranges and candle windowing. - Series engines: candlestick, OHLC bar, line, area, baseline, histogram, volume. - Magnet crosshair: pointer-to-candle snapping and price read-out. - Platform-agnostic Scenedisplay list shared with the Compose and SwiftUI ports.