Update agent & flow list item components for use in Explore and Project areas

We want the user's experience of project and explore-level list items for agents and flows to be intuitive and consistent with other GitLab UI elements and areas.

Questions:

• What actions are available to put into the overflow menu?

• Remove overflow menu in the Explore area
• Do not change overflow menu in Projects area in this issue

• Check metadata fields (number of runs, starred, usage metrics in general…) that we could display (or suggest to UX for display)

• This was a UX question as we were discovering what this change would entail, but this issue will not implement any new metadata

Data to display (as shown in the image below) are:

• name of agent or flow
• description
• public (w/ icon)

Removed from the discussion due to not being ready:

• @mention tag (doesn't exist yet)
• "Made by GitLab" icon (tanuki-verified icon)
• author/createdBy (w/ user icon or avatar -- not available)

Updated look/feel as of 2025-10-14:

Old: