[lviobio]

Opening docked DevTools can shrink the viewport below the mobile breakpoint, leaving the sidebar collapsed after DevTools closes. Viewport clamping also overwrote the saved sidebar width.

Restore the saved desktop collapse preference when returning from a narrow viewport, and clamp only the rendered width so the chosen width returns as space becomes available. Manual resizing continues to update the saved width.

Validation:

• All 32 sidebar Playwright tests passed on the development server, including five new viewport-resize regressions covering restoration, manual collapse, narrow-viewport reloads, and dragged-width persistence.
• The two restoration regressions failed before the fix.
• npm run build passed.
• git diff --check passed.