LiveView DOM patching was stripping the client-side sidebar-collapsed
class from #sidebar-wrapper on every navigation. Fix: put the class
on document.documentElement which LiveView never touches.
- Sync script in <head> applies state before first paint (no flash)
- Hook click handler toggles on <html> + saves to localStorage
- CSS selectors updated to html.sidebar-collapsed
- Removed phx-click JS.toggle_class (hook handles toggle directly)
