feat: add PageHeader component and centralize page spacing

- Create reusable PageHeader component (emoji + title + subtitle + actions)
- Use PageHeader in sessions, teams, users, objectives pages
- Centralize vertical padding in layout (py-6) and remove per-page py-* values

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

src/app/gif-mood/new/page.tsx

@@ -20,7 +20,8 @@ export default function NewGifMoodPage() {
   const [error, setError] = useState<string | null>(null);
   const [selectedDate, setSelectedDate] = useState(new Date().toISOString().split('T')[0]);
   const [title, setTitle] = useState(
-    () => `GIF Mood - ${new Date().toLocaleDateString('fr-FR', { day: 'numeric', month: 'long', year: 'numeric' })}`
+    () =>
+      `GIF Mood - ${new Date().toLocaleDateString('fr-FR', { day: 'numeric', month: 'long', year: 'numeric' })}`
   );
 
   async function handleSubmit(e: React.FormEvent<HTMLFormElement>) {
@@ -48,11 +49,11 @@ export default function NewGifMoodPage() {
   }
 
   return (
-    <main className="mx-auto max-w-2xl px-4 py-8">
+    <main className="mx-auto max-w-2xl px-4">
       <Card>
         <CardHeader>
           <CardTitle className="flex items-center gap-2">
-            <span>🎭</span>
+            <span>🎞️</span>
             Nouveau GIF Mood Board
           </CardTitle>
           <CardDescription>