localization: fix two defects found by actually rendering the shipped locales

Neither was visible from the source or from any test — both only showed up
switching the live UI to es-ES/de-DE/fr-FR in a browser, which is what
turned up the catalogue-wiring bug this builds on top of (see prior commit).

1. FileItem.tsx had two `isDir ? 'Folder' : ...` ternaries the scanner
   cannot see (values computed inside a JSX expression, not JSX text) —
   the Type column and the grid-view size line both showed the English
   word "Folder" regardless of locale. New key files.grid.folderType,
   translated in all five catalogs.

2. files.menu.selected was a single hardcoded string ("selected" /
   "seleccionados" / "sélectionnés" / ...), not a plural form. English
   doesn't inflect "selected" for number so this was invisible in the
   source locale, but Spanish and French do: "1 seleccionados" and
   "1 sélectionnés" are both wrong, should be singular. Converted to a
   {one, other} pair in all five locales (pt-PT included — same bug,
   pre-existing) and updated SelectionActions.tsx to pass count. German
   was fine either way ("ausgewählt" doesn't inflect here).

Verified by minting a token for the owner's own account, driving a
headless browser through es-ES/de-DE/fr-FR at /settings/profile, /files,
and the file context menu, and reading the screenshots — not just running
the test suite. Owner's real settings were read before and restored after.

src/workspaces/officerdev/src/apps/FileBrowser/FileBrowserApp/components/FileItem.tsx

@@ -588,6 +588,7 @@ export const FileItem = ({
   isPinned,
   canPaste,
 }: FileItemProps) => {
+  const { t } = useTranslation();
   const { date } = useFormat();
   const [renaming, setRenaming] = useState(false);
   const clickTimer = useRef<ReturnType<typeof setTimeout> | null>(null);
@@ -720,7 +721,7 @@ export const FileItem = ({
               )}
             </div>
             <span className="hidden md:inline text-xs text-duck-dark/50 shrink-0 w-20 text-right">
-              {isDir ? 'Folder' : getFileType(entry.name).replace(/^\w/, (c) => c.toUpperCase())}
+              {isDir ? t('files.grid.folderType') : getFileType(entry.name).replace(/^\w/, (c) => c.toUpperCase())}
             </span>
             <span className="hidden md:inline text-xs text-duck-dark/50 shrink-0 w-20 text-right">
               {isDir ? '--' : formatSize(entry.size)}
@@ -774,7 +775,7 @@ export const FileItem = ({
           )}
 
           <span className="text-xs text-duck-dark/50">
-            {isDir ? 'Folder' : formatSize(entry.size)}
+            {isDir ? t('files.grid.folderType') : formatSize(entry.size)}
             {' · '}
             {date(entry.modifiedAt, { month: 'short', day: 'numeric', year: 'numeric' })}
           </span>

src/workspaces/officerdev/src/apps/FileBrowser/FileBrowserApp/components/Toolbar/SelectionActions.tsx

@@ -23,7 +23,7 @@ export const SelectionActions = ({ fileBrowserManager }: SelectionActionsProps)
     <>
       <span className="text-sm font-medium text-duck-dark/70 mr-1">
         {selected.size}
-        <span className="hidden md:inline"> {t('files.menu.selected')}</span>
+        <span className="hidden md:inline"> {t('files.menu.selected', { count: selected.size })}</span>
       </span>
       <button
         onClick={handleCut}

src/workspaces/officerdev/src/locales/de-DE.json

@@ -512,12 +512,16 @@
       "gitClone": "Git-Klon",
       "searchFiles": "Dateien durchsuchen...",
       "clearSelection": "Auswahl aufheben",
-      "selected": "ausgewählt",
+      "selected": {
+        "one": "ausgewählt",
+        "other": "ausgewählt"
+      },
       "refresh": "Aktualisieren"
     },
     "grid": {
       "empty": "Dieser Ordner ist leer",
       "sort": "Sortieren:",
+      "folderType": "Ordner",
       "name": "Name",
       "type": "Typ",
       "size": "Größe",

src/workspaces/officerdev/src/locales/en-GB.json

@@ -512,12 +512,16 @@
       "gitClone": "Git clone",
       "searchFiles": "Search files...",
       "clearSelection": "Clear selection",
-      "selected": "selected",
+      "selected": {
+        "one": "selected",
+        "other": "selected"
+      },
       "refresh": "Refresh"
     },
     "grid": {
       "empty": "This folder is empty",
       "sort": "Sort:",
+      "folderType": "Folder",
       "name": "Name",
       "type": "Type",
       "size": "Size",

src/workspaces/officerdev/src/locales/es-ES.json

@@ -512,12 +512,16 @@
       "gitClone": "Clonar con Git",
       "searchFiles": "Buscar archivos...",
       "clearSelection": "Limpiar selección",
-      "selected": "seleccionados",
+      "selected": {
+        "one": "seleccionado",
+        "other": "seleccionados"
+      },
       "refresh": "Actualizar"
     },
     "grid": {
       "empty": "Esta carpeta está vacía",
       "sort": "Ordenar:",
+      "folderType": "Carpeta",
       "name": "Nombre",
       "type": "Tipo",
       "size": "Tamaño",

src/workspaces/officerdev/src/locales/fr-FR.json

@@ -512,12 +512,16 @@
       "gitClone": "Cloner via Git",
       "searchFiles": "Rechercher des fichiers...",
       "clearSelection": "Effacer la sélection",
-      "selected": "sélectionnés",
+      "selected": {
+        "one": "sélectionné",
+        "other": "sélectionnés"
+      },
       "refresh": "Actualiser"
     },
     "grid": {
       "empty": "Ce dossier est vide",
       "sort": "Trier :",
+      "folderType": "Dossier",
       "name": "Nom",
       "type": "Type",
       "size": "Taille",

src/workspaces/officerdev/src/locales/pt-PT.json

@@ -512,12 +512,16 @@
       "gitClone": "Clonar via Git",
       "searchFiles": "Pesquisar ficheiros...",
       "clearSelection": "Limpar seleção",
-      "selected": "selecionados",
+      "selected": {
+        "one": "selecionado",
+        "other": "selecionados"
+      },
       "refresh": "Atualizar"
     },
     "grid": {
       "empty": "Esta pasta está vazia",
       "sort": "Ordenar:",
+      "folderType": "Pasta",
       "name": "Nome",
       "type": "Tipo",
       "size": "Tamanho",