Add FundedNext Integration for Account Connection

Implement FundedNext Server Support for Prop Firm Account Connectivity.

Users need the ability to connect their FundedNext trading accounts to PF1, but FundedNext is currently not available as a server option in the account connection interface. This feature would add FundedNext to the list of supported brokers/servers within PF1's connectivity options, enabling users to link their FundedNext accounts for comprehensive trading analytics, performance tracking, and portfolio management alongside their other prop firm and personal accounts. The integration should support all standard PF1 functionality including trade importing, real-time data synchronization, performance metrics, and dashboard reporting to ensure FundedNext account holders can fully utilize the platform's trading analytics and management capabilities.