Add EVM send confirmation and signing modal

[Texaglo]

Summary

Add an explicit confirmation modal before an EVM asset transfer is locally signed and broadcast. The flow reuses the established Liberdus send-confirmation UI while keeping EVM-specific details and event handling isolated in evm-assets.js.

Closes #1531

Changes

• add a dedicated EvmSendConfirmationModal adapter
• reuse the existing send-confirmation modal without changing the Liberdus wallet flow
• display the EVM network and chain ID
• display the asset, amount, estimated USD value, recipient, and maximum network fee
• retain a Liberdus username in confirmation instead of exposing its internally resolved EVM address
• explain that wallet signing happens locally and the private key does not leave the device
• require explicit confirmation before signing or broadcasting
• intercept Confirm, Cancel, Back, and browser-back actions only while an EVM confirmation is pending
• safely re-enable the EVM send form after cancellation
• reset any pending confirmation when EVM Assets state is reset
• keep all implementation changes isolated to evm-assets.js

Validation

• node --check evm-assets.js
• node --check app.js
• git diff --check origin/main...HEAD
• confirmation cancellation smoke test verifies:
  • the username display label is retained
  • cancellation returns a cancelled status
  • no raw transaction is broadcast
• local browser validation verifies:
  • the BNB send confirmation displays recipient, amount, USD estimate, network, fee, and local-signing notice
  • Cancel safely returns to the send form
  • Back safely returns to the send form
  • no transaction is broadcast during cancellation testing

Scope

No backend, HTML, CSS, or Liberdus wallet files are changed. No live transaction was broadcast during validation.