fix(storage): default defParamCharset to utf8 in the upload factory

server/src/nest/storage/storage-upload.factory.ts

@@ -36,7 +36,7 @@ export interface StorageUploadOptions {
    * the pre-factory call sites).
    */
   filename?: (req: Request, file: Express.Multer.File) => string;
-  /** Parity-phase opt-in (files + collab pass 'utf8'). */
+  /** Always 'utf8' since fix #3; the option remains for explicit callers. */
   defParamCharset?: 'utf8';
 }
 
@@ -63,6 +63,8 @@ export function buildStorageUploadOptions(storage: StorageService, opts: Storage
     }),
     limits: { fileSize: opts.maxSize },
     ...(opts.fileFilter ? { fileFilter: opts.fileFilter } : {}),
-    ...(opts.defParamCharset ? { defParamCharset: opts.defParamCharset } : {}),
+    // Uniform since fix #3: non-ASCII original filenames decode as UTF-8 on
+    // every upload route (previously only trip files + collab opted in).
+    defParamCharset: opts.defParamCharset ?? 'utf8',
   };
 }

server/tests/unit/nest/storage/storage-upload.factory.test.ts

@@ -151,10 +151,10 @@ describe('buildStorageUploadOptions', () => {
     expect('fileFilter' in without).toBe(false);
   });
 
-  it('STORAGE-UPLOAD-010 — defParamCharset is absent unless passed, utf8 when passed', () => {
+  it('STORAGE-UPLOAD-010 — defParamCharset defaults to utf8 everywhere (fix #3)', () => {
     const storage = { spoolDirFor: () => dirA } as unknown as StorageService;
     const without = buildStorageUploadOptions(storage, { category: 'files', maxSize: 10 });
-    expect('defParamCharset' in without).toBe(false);
+    expect((without as { defParamCharset?: string }).defParamCharset).toBe('utf8');
 
     const withCharset = buildStorageUploadOptions(storage, { category: 'files', maxSize: 10, defParamCharset: 'utf8' });
     expect((withCharset as { defParamCharset?: string }).defParamCharset).toBe('utf8');