`clearProfileData` returned silently when no environment was connected, while
the menu item stayed enabled — a dead control with no explanation. It now
reports the same way `importInto` does for the same precondition.

Also switches `browserImport` to the subpath namespace import the rest of
`packages/contracts` uses.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>