Bug: Links from FreeCAD app

### Bug description

In the FreeCAD help menu there are a few website links (e.g. "sponsor"). It seems the new site uses different page names.

Will you rename or redirect those or shall we change the links before the 26.3 release in the app?

### Page collection affected

Homepage

### Steps to reproduce

Open FreeCAD, click on external links, e.g. donate

### System affected

All

Start by reproducing the broken links from the FreeCAD help menu, especially the donate or sponsor links, and inspect the corresponding homepage links in this Hugo website. Compare their destinations with the new page names and determine whether the website links can be renamed or redirected. Done means the affected links work from the app before the 26.3 release.

Written by the indexing model from the issue text.