Fix Quick Connect duplication and modal close icons

[bifrost0x]

Summary

• remove the duplicate top-right Quick Connect action while keeping the central launcher and the + button
• route the remaining Quick Connect entry points directly to the default-pane connection modal
• restore Material Icons rendering for modal close controls and refresh the affected asset cache keys

Scope

• addresses Number of "Quick Connect" buttons #133
• fixes the reported close-control bug from WebSSH 2.0 UI design questions #134
• leaves the broader Hosts and Commands redesign for a separate follow-up

Testing

• python -m pytest tests -q (1844 passed, 33 skipped)
• npm run test:js (286 passed)
• npm run lint:js
• npm run vendor:check
• npm run test:e2e -- --workers=2 (85 passed)