FE: Display source project attribution on AI Catalog agent/flow cards

Summary

Add source project attribution to AI Catalog agent and flow cards in both Explore and Project views. This is a quick-win feature that provides valuable context to users about which project owns each catalog item.

Background

During discussion in #579728, the team decided to show source project attribution instead of individual author attribution because:

• Individual attribution is ambiguous in multi-contributor workflows
• The project represents those with appropriate permissions to modify/delete the agent/flow
• Project data is already available via GraphQL
• This aligns with UX designs showing project ownership on catalog cards

Design

See design mockup in parent issue discussion showing project attribution on catalog cards.

Implementation Notes

• Project data is returned by GraphQL but can be null, so must be treated as nullable
• This should be implemented for both agent and flow cards
• Display in both Explore and Project catalog views

Acceptance Criteria

• Source project is displayed on agent cards when available
• Source project is displayed on flow cards when available
• Null project values are handled gracefully (no display or appropriate fallback)
• Implementation works in both Explore and Project catalog views
• Design matches UX mockups

Related Issues

• Parent issue: #579728