refactor: Phase E — types de réponses API standardisés + SVGs inline → Icon

E1 - API responses:
- Crée responses.rs avec OkResponse, DeletedResponse, UpdatedResponse,
  RevokedResponse, UnlinkedResponse, StatusResponse (6 tests de sérialisation)
- Remplace ~15 json!() inline par des types structurés dans books, libraries,
  tokens, users, handlers, anilist, metadata, download_detection, torrent_import
- Signatures de retour des handlers typées (plus de serde_json::Value)

E2 - SVGs → Icon component:
- Ajoute icon "lock" au composant Icon
- Remplace ~30 SVGs inline par <Icon> dans 9 composants
  (FolderPicker, FolderBrowser, LiveSearchForm, JobRow, LibraryActions,
  ReadingStatusModal, EditBookForm, EditSeriesForm, UserSwitcher)

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

apps/backoffice/app/components/FolderBrowser.tsx

@@ -3,6 +3,7 @@
 import { useState, useCallback } from "react";
 import { FolderItem } from "../../lib/api";
 import { useTranslation } from "../../lib/i18n/context";
+import { Icon } from "./ui";
 
 interface TreeNode extends FolderItem {
   children?: TreeNode[];
@@ -116,14 +117,7 @@ export function FolderBrowser({ initialFolders, selectedPath, onSelect }: Folder
                   <path className="opacity-75" fill="currentColor" d="M4 12a8 8 0 018-8V0C5.373 0 0 5.373 0 12h4zm2 5.291A7.962 7.962 0 014 12H0c0 3.042 1.135 5.824 3 7.938l3-2.647z"></path>
                 </svg>
               ) : (
-                <svg
-                  className={`w-3 h-3 transition-transform duration-200 ${isExpanded ? 'rotate-90' : ''}`}
-                  fill="none"
-                  stroke="currentColor"
-                  viewBox="0 0 24 24"
-                >
-                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 5l7 7-7 7" />
-                </svg>
+                <Icon name="chevronRight" size="sm" className={`!w-3 !h-3 transition-transform duration-200 ${isExpanded ? 'rotate-90' : ''}`} />
               )}
             </button>
           ) : (
@@ -153,9 +147,7 @@ export function FolderBrowser({ initialFolders, selectedPath, onSelect }: Folder
 
           {/* Selected indicator */}
           {isSelected && (
-            <svg className="w-4 h-4 text-primary flex-shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
-            </svg>
+            <Icon name="check" size="sm" className="text-primary flex-shrink-0" />
           )}
         </div>