fix(uploads): allow non-document execution outputs in presigned route

The execution branch of the presigned upload route called validateFileType,
which only permits documents — but workflow execution outputs are arbitrary
by design (images, audio, video, code). The legacy /api/files/upload
execution branch had no docs-only gate, so the staging refactor to
presigned PUTs regressed parity. Switch execution to validateAttachmentFileType
to match prior behavior.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: waleedlatif1

apps/sim/app/api/files/presigned/route.ts

@@ -175,7 +175,7 @@ export const POST = withRouteHandler(async (request: NextRequest) => {
         )
       }
 
-      const fileValidationError = validateFileType(fileName, contentType)
+      const fileValidationError = validateAttachmentFileType(fileName)
       if (fileValidationError) {
         throw new ValidationError(fileValidationError.message)
       }