Add file management API with local storage backend

- Implement FileHandler with CRUD operations for files/directories
- Add FileService with business logic and SHA-256 hashing
- Create LocalStorage backend for filesystem persistence
- Add database repository with pagination and name uniqueness
  constraints
- Configure max upload size in storage settings
- Include comprehensive tests for all layers

internal/server/server_test.go

@@ -21,7 +21,7 @@ func TestVersionRoute(t *testing.T) {
 		},
 	}
 	authService := service.NewAuthService(nil, nil, nil, nil, 15*time.Minute, 7*24*time.Hour)
-	webApp := app.NewWebApp(cfg, nil, nil, nil, nil, nil, authService)
+	webApp := app.NewWebApp(cfg, nil, nil, nil, nil, nil, authService, nil, nil)
 	router := NewRouter(webApp)
 
 	req := httptest.NewRequest(http.MethodGet, "/api/v1/version", nil)