test: update tests to use English translation strings

Tests were asserting against hardcoded German strings that were replaced
with t() calls. Updated to match the English translation values rendered
by TranslationProvider in the test environment.

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

client/src/pages/FilesPage.test.tsx

@@ -100,7 +100,7 @@ describe('FilesPage', () => {
         expect(screen.getByTestId('file-manager')).toBeInTheDocument();
       });
 
-      expect(screen.getByText(/2 Dateien/)).toBeInTheDocument();
+      expect(screen.getByText(/2 files for/i)).toBeInTheDocument();
     });
   });
 
@@ -205,7 +205,7 @@ describe('FilesPage', () => {
         expect(screen.getByTestId('file-manager')).toBeInTheDocument();
       });
 
-      expect(screen.getByRole('heading', { name: /Dateien & Dokumente/i })).toBeInTheDocument();
+      expect(screen.getByRole('heading', { name: /Files & Documents/i })).toBeInTheDocument();
     });
   });
 });

client/src/pages/PhotosPage.test.tsx

@@ -118,7 +118,7 @@ describe('PhotosPage', () => {
         expect(screen.getByTestId('photo-gallery')).toBeInTheDocument();
       });
 
-      expect(screen.getByText(/1 Fotos/)).toBeInTheDocument();
+      expect(screen.getByText(/1 photos for/i)).toBeInTheDocument();
     });
   });
 
@@ -224,7 +224,7 @@ describe('PhotosPage', () => {
         expect(screen.getByTestId('photo-gallery')).toBeInTheDocument();
       });
 
-      expect(screen.getByRole('heading', { name: /fotos/i })).toBeInTheDocument();
+      expect(screen.getByRole('heading', { name: /photos/i })).toBeInTheDocument();
     });
   });
 });