Add lightweight chart indicators

[Sikkra]

Closes #16.

Summary:

• Adds a persisted chart indicator menu to the existing chart toolbar.
• Supports SMA 20, EMA 20, RSI 14 with 70/30 guide lines, and MACD with signal line and histogram using the existing lightweight-charts dependency.
• Recomputes indicator series when candles load, the market/resolution changes, or live candle updates arrive.
• Keeps the OHLC hover panel bound to the candlestick series only, so indicator hover values do not overwrite OHLC display.

Verification:

• npm run build passes.
• Local browser check: trade UI loads and the Indicators control is present. Full click-through is blocked in my environment by the app's existing restricted-country overlay, which sits above the chart controls.