Enhance TP/SL order inputs

[qq33357486]

Fixes #17.

Summary

• adds quick TP/SL price-move buttons (+1%, +2%, +5%) to the new order advanced options
• shows estimated P/L amount and percent for both take-profit and stop-loss inputs
• keeps manual TP/SL price and percent entry working, clearing the highlighted quick button when users edit manually

Validation

• npm run build
• Opened the local build at /trade/ETH-USD and verified the advanced order panel renders the new TP/SL controls

Disclosure: AI assisted implementation, manually reviewed and built before submission.