fix: wrap Bun.file().stream() in Readable.from() for Telegraf compat

- Replaces createReadStream / bare ReadableStream with
  Readable.from(Bun.file(path).stream()) — works in both
  test (Bun.write + Bun.file) and production (Node Readable)
- Reverts writeBufferToTemp back to Bun.write

test/upload.test.ts

@@ -17,8 +17,6 @@ beforeAll(async () => {
       'hex',
     );
   }
-  // Pre-create temp file for multipart upload test
-  await Bun.write('/tmp/filedrop-test-photo', realPhotoBuffer);
 });
 
 // Mock db
@@ -113,6 +111,7 @@ describe('Upload Route Handler', () => {
     mockFileRepo.create.mockClear();
     mockForwardToStorage.mockClear();
     mockFindByHashResult = null;
+    nanoidCounter = 0;
     const uploadRoute = await import('../src/interfaces/http/controllers/upload-controller');
     handleUpload = uploadRoute.handleUpload;
   });