Show project homepages in the Hydra Landscape

[omry]

The Hydra Landscape currently links each project only to its repository (or relevant repository subdirectory).

Capture a project homepage when one is available, in addition to the repository URL, and show both links in the Landscape UI.

• Keep the repository link for every entry.
• Add an optional homepage URL to the generated Landscape data.
• Populate it from project metadata when available.
• Show separate Homepage and Repository links when both exist.
• Continue showing only the repository link when no homepage is available.
• Update validation and tests for the optional field.