Corrected a small typo that caused the Odoo mobile app to show a blank page on iOS devices. This improves reliability for users accessing Odoo through Safari, which is stricter about this type of error.

This fix an issue in the mobile app in iOS.
Safari is less permissive and a blank page was shown.

Fixes an issue in Odoo Sign where trying to open a PDF through an image-only route could cause a crash. PDFs are now handled through the correct content path, improving reliability when users access signed documents.

[FIX] sign: fix crash trying to access pdf through image route