Polish Codex account icon alignment

[yvette-carlisle]

Summary

• replace the Codex account summary icon with a simpler terminal symbol
• align account metric icons to the text baseline with a shared SwiftUI helper
• apply the same alignment treatment to matching account summary/profile/warning rows

Verification

• swift test --package-path apps/decodex-app
• git diff --check
• cargo make test-decodex-app-stage
• staged app visual screenshot: /tmp/decodex-icon-polish-summary4.png
• WebUI mock dashboard visual check: /tmp/decodex-webui-dashboard-current.png

WebUI was inspected and did not need code changes.