fix: separate ladder plan status fields

[jackhai9]

Summary

• separate ladder ratio, order count, and interval with spaced middle dots
• label all three plan fields explicitly and keep the interval visible at its default value
• add source regression coverage for the approved copy contract

Validation

• npm test
• npm run test:ui
• npm run build:binance-orderbook-trade
• npm run check:binance-orderbook-trade
• npm run inspect:binance-orderbook-trade
• git diff --check