Detailed Transaction Fee Breakdown Display

[JoyLight00]

Background
Users need clear insights on exactly where their XLM is going (escrow balance vs. network gas fees vs. platform commission) before committing.

Goal
Build a detailed fee table inside the funding checkout modal.

Acceptance Criteria

• Render rows showing: Initial deposit amount, Estimated Soroban Gas, Platform Service Fee (e.g. 2%), Total amount to lock.

Key Files
src/components/marketplace/FundSessionModal.tsx