fix(library): splice au lieu d'assignation pour Alpine 3.14.9 x-for

Alpine 3.14.9 ne détecte pas le changement de référence d'array
(this.flatItems = result). Utilisation de splice() pour muter
l'array en place. Ajout de $nextTick pour forcer le re-render.

app/templates/library.html

@@ -379,7 +379,8 @@ function libraryPage() {
           return (r.title || '').toLowerCase().indexOf(q) !== -1;
         });
       }
-      this.flatItems = result;
+      // Use splice for Alpine 3.14.9 reactivity (array reference reassign fails)
+      this.flatItems.splice(0, this.flatItems.length, ...result);
       this.selectedCount = Object.keys(this.selected).length;
       this.allSelected = this.flatItems.length > 0 && this.selectedCount === this.flatItems.length;
     },
@@ -483,11 +484,14 @@ function libraryPage() {
         this._markTree(this.items, 0);
         this._recomputeFlatItems();
         console.log('[Library] flatItems after recompute: ' + this.flatItems.length);
+        // Force Alpine to re-render (known issue with x-for in 3.14.9)
+        var self = this;
+        this.$nextTick(function() { self.loading = false; });
       } catch(e) {
         console.error('[Library] load error:', e);
         this.items = [];
+        this.loading = false;
       }
-      this.loading = false;
     },
 
     _markTree(nodes, depth) {