Use explicit navigator.clipboard check instead of optional chaining so
the no-op case is handled explicitly. When clipboard API is unavailable
(non-HTTPS context) show a toast: "Copy requires HTTPS — please select
and copy manually". Production is always HTTPS so this only affects
local dev with http:// canvas.
Closes#1199.
Co-authored-by: Molecule AI Core-FE <core-fe@agents.moleculesai.app>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>