feat: clickable character cards, default character, rename Archivio → Libreria

- CharacterList: entire card is clickable to enter edit mode
- CharacterList: uses ConfirmModal for delete (replaces browser confirm)
- CharacterList: action buttons stop propagation to avoid double-nav
- ContentPage: auto-selects first active character as default
- Rename "Archivio Contenuti" → "Libreria Contenuti" everywhere
- Mobile-safe grid for character cards

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/components/ContentPage.jsx

@@ -69,14 +69,22 @@ export default function ContentPage() {
     api.get('/characters/').then(d => {
       setCharacters(d)
       setCharsLoading(false)
+
+      // Auto-select default character (first active one)
+      const activeChars = d.filter(c => c.is_active)
+      const defaultChar = activeChars.length > 0 ? String(activeChars[0].id) : ''
+
       // One-click flow: pre-fill from URL params
       const urlTopic = searchParams.get('topic')
       const urlCharacter = searchParams.get('character')
       if (urlTopic && d.length > 0) {
-        const charId = urlCharacter || String(d[0].id)
+        const charId = urlCharacter || defaultChar
         setForm(prev => ({ ...prev, character_id: charId, topic_hint: urlTopic }))
         autoGenerateRef.current = true
-        setSearchParams({}, { replace: true })  // clean URL
+        setSearchParams({}, { replace: true })
+      } else if (defaultChar) {
+        // Pre-select default character
+        setForm(prev => ({ ...prev, character_id: prev.character_id || defaultChar }))
       }
     }).catch(() => setCharsLoading(false))
   }, [])
@@ -205,7 +213,7 @@ export default function ContentPage() {
             Definisci un brief editoriale, scegli piattaforma e tipo, poi genera. L'AI terrà conto del tono e dei topic del personaggio selezionato.
           </p>
           <Link to="/content/archive" style={{ fontSize: '0.8rem', color: 'var(--accent)', whiteSpace: 'nowrap', textDecoration: 'none', fontWeight: 600 }}>
-            Archivio →
+            Libreria →
           </Link>
         </div>
       </div>