I need to add a css file or javascript to each of the NetSuite pages to make the page direction RTL. I tried adding it through :
SuiteScript >> Client >> Deployment : All Records,
And already succeeded in adding them to some pages. But I need to add the code to all pages of the NetSuite.
NetSuite does not provide an option to add CSS/JS to every page. Only certain pages are scriptable as you have discovered.
You could use something like Tamerpermonkey to achieve this. However that would require installation on each end user's machine.