fix: wrap multiline extension status text

[y4ho0]

Summary

• preserve line breaks in extension status text while still normalizing horizontal whitespace
• let long status lines wrap instead of truncating them behind an ellipsis
• cap tall status output at the same 144px / 18dvh limit used by extension widgets, with internal scrolling for additional lines
• add regressions for text normalization and the wrapping/scrolling CSS contract

User impact

Extensions that publish multiline status output, such as /wechat-status, are now readable in Pi Web. Short single-line statuses keep the existing compact 35px footer, while large status reports no longer cover the chat area.

Validation

• npm test — 588 passed
• node_modules/.bin/tsc --noEmit
• npm run lint
• local browser check: single-line footer remained 35px; multiline text preserved line breaks and wrapped; output above 144px scrolled inside the footer

Closes #524