Show project icons in the linked PR list for a thread

[nathanscain]

Problem or use case

The PR/MR list opened from a thread can contain work from several repositories, but it is hard to tell which repo or project each row belongs to at a glance. Repository information appears in small secondary text that is often truncated.

This is especially common when a coordinator thread is rolling out the same patch to many repositories at once. The resulting PRs often have identical or very similar titles, so the thread's linked list becomes a series of nearly indistinguishable rows.

Proposal

Show the associated T3 project's icon on each row in the thread's linked PR list when its repository is tied to a T3 project. For a thread coordinating work across several projects, each row would use its own project's icon, making the list easier to scan even when the titles are identical.