Added aria-labels to interactive buttons across trading pages

Added descriptive `aria-label` attributes to all interactive buttons (filter, export, refresh, sort, cancel, modify) that lacked accessible names, making them inaccessible to screen reader users.

Description

OpenAlgo is an open-source algorithmic trading platform that provides a unified API layer across 24+ Indian brokers (Zerodha, Dhan, Angel, etc.), enabling seamless integration with TradingView, Amibroker, Python, and AI agents. Built with Flask and React 19. My Contribution: Fixed a web accessibility (WCAG 2.1) issue — added descriptive aria-label attributes to 15 interactive buttons across 4 pages (Holdings, OrderBook, Positions, TradeBook) that were inaccessible to screen reader users. The fix ensures all icon-only buttons announce their action (e.g., "Cancel order", "Refresh positions") instead of being silent, improving the platform's accessibility for visually impaired users.