Security: Payout Precision & Accuracy Fix

[MichaelSovereign]

Summary

This PR fixes a potential floating-point precision vulnerability in the payout validation logic.

Changes

1. Decimal Migration: Replaced with for all financial calculations and amount quantization. This ensures that small amounts (micro-RTC) are calculated with absolute accuracy, preventing rounding errors that could lead to failed transfers or incorrect fund amounts.
2. Safe Parsing: Added helper to handle input sanitization using Decimal types.

Closes #7457