#2963 stagecraft studio: long work-item keys overflow Board cards, and the built-in tracker ref repeats the key

On the studio Board (#2943), a work item card's key, and its tracker ref, are long strings with no spaces. They overflow the card and break the column layout.

What happened

Seth saw this on 2026-10-02 at /f/blog/board, on main at d0b460c46. GET /api/work-items?factory=blog returns:

• key: blog-using-stagecraft-organizing-shipping-blog-posts-6r6t (59 characters)
• trackerRef: the same 59 characters. On the built-in tracker, a ticket's id is the work item's key, so the card shows it twice.
• title: "Using stagecraft for organizing and shipping blog posts". This wraps normally.

Keys are slugs of the whole title, so 50 to 64 characters is normal (DESIGN.md, "Keys are stagecraft's": up to 64, the factory prefix cut at 55). The board has to handle that.

Fix

1. The title is the card's headline. It wraps normally.

2. The key goes on a single line, cut off with an ellipsis. Show the full key in a tooltip and an accessible label, and in Copy reference.

3. Show the tracker ref only when it differs from the key, that is, for a real external id such as Linear's ABC-12. Never repeat the key.

4. Add a backstop on every text element in a card: min-width: 0 on flex and grid children, and overflow-wrap: anywhere. No string can widen a column.

5. Check the other places the key or tracker ref appears:

   • the work-item view (#2944, in progress; coordinate with it so it doesn't ship the same bug);
   • Simulate's panels;
   • the factory picker.

   Apply the same rules wherever they're needed.

Done when

• A studio test renders the board with a 64-character key and a long title. It checks that the card's width stays within its column, that the key is cut off with its full text available, and that a tracker ref equal to the key isn't shown.
• Seth's blog factory board displays cleanly.
• Keyboard and screen-reader access to the full key is kept (WCAG 2.2 AA).

Out of scope: shortening keys themselves (a design question for later).