Aggiunge pannello info app (bottom sheet)

- InfoPanel.vue: bottom sheet con nome, versione (da package.json),
  autore (Davide Grilli), licenza EUPL v1.2 e link documentazione
- App.vue: bottone info fisso in alto a destra, visibile da tutte
  le pagine, con animazione slide-up sul pannello

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

src/App.vue

@@ -4,17 +4,30 @@
     <Converter   v-else-if="page === 'convert'" />
     <ShoppingList v-else-if="page === 'shop'" />
     <BottomNav v-model="page" />
+
+    <!-- bottone info fisso in alto a destra -->
+    <button class="btn-info" @click="showInfo = true" aria-label="Informazioni app">
+      <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+        <circle cx="12" cy="12" r="10"/>
+        <line x1="12" y1="16" x2="12" y2="12"/>
+        <line x1="12" y1="8" x2="12.01" y2="8"/>
+      </svg>
+    </button>
+
+    <InfoPanel v-model="showInfo" />
   </div>
 </template>
 
 <script setup>
 import { ref } from 'vue'
 import BottomNav    from './components/BottomNav.vue'
+import InfoPanel    from './components/InfoPanel.vue'
 import MealPlanner  from './pages/MealPlanner.vue'
 import Converter    from './pages/Converter.vue'
 import ShoppingList from './pages/ShoppingList.vue'
 
 const page = ref('meal')
+const showInfo = ref(false)
 </script>
 
 <style scoped>
@@ -22,5 +35,33 @@ const page = ref('meal')
   height: 100dvh;
   display: flex;
   flex-direction: column;
+  position: relative;
+}
+
+.btn-info {
+  position: fixed;
+  top: 14px;
+  right: 16px;
+  /* centra rispetto al max-width del layout */
+  max-width: calc(480px);
+  background: var(--color-surface);
+  color: var(--color-muted);
+  min-height: 36px;
+  min-width: 36px;
+  padding: 0;
+  border-radius: 50%;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  box-shadow: var(--shadow-sm);
+  border: 1px solid var(--color-border);
+  z-index: 50;
+  transition: color var(--transition), box-shadow var(--transition);
+}
+
+.btn-info:active {
+  color: var(--color-primary);
+  box-shadow: var(--shadow-md);
+  opacity: 1;
 }
 </style>