Explain iETH and where protocol swaps execute

Consolidates feedback tickets #145 (https://app.notion.com/3b199411cf9081d7ad0cce3f6869b5bd) and #147 (https://app.notion.com/3b199411cf90819faa3cec7aa6896352). Reported after successful swaps on Chrome and iOS.

## Problem

Users can complete a MIDEN → iETH swap but are left asking:

- What is iETH?
- How does it relate to ETH?
- Where did the exchange execute?
- What does “protocol DEX” mean in practical terms?

## Expected

Before confirmation and in the result/detail view, explain the output asset and execution venue in concise user-facing language. The explanation should be sufficient for someone who is not already familiar with Miden’s asset naming or native DEX.

Feedback DB refs: tickets 145 and 147.

Look for the UI components that display swap confirmation and result details, likely in the frontend codebase. Find where iETH and 'protocol DEX' are mentioned in the user interface. The task is to add explanatory text in those views, using concise, user-friendly language. Check the linked feedback tickets #145 and #147 for more context on the user confusion.

由索引模型根据 Issue 内容生成。