fix(preventivo): slide deck 100vh — nessuno scroll di pagina

- ProposalDeck: outer div h-screen overflow-hidden, content wrapper h-full
- Rimosso il div interno ridondante min-h-screen
- useEffect blocca body overflow mentre la deck è aperta
- Tutti i 20 componenti slide: min-h-screen → h-full

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/public/proposal/sections/TimelineSection.tsx

@@ -12,7 +12,7 @@ export function TimelineSection({ timeline }: Props) {
   const weeks = Array.from({ length: timeline.totalWeeks }, (_, i) => i + 1);
 
   return (
-    <div className="min-h-screen flex flex-col justify-center px-16 py-24 space-y-10">
+    <div className="h-full flex flex-col justify-center px-16 py-24 space-y-10">
       <div>
         <p className="text-xs font-mono tracking-widest text-muted-foreground uppercase">Timeline</p>
         <h2 className="text-5xl font-light text-foreground mt-4">