A hot-file hold names the open pulls on that file, oldest first, on the map and in the Flow panel

Intent: when the map says a file is in 5 open pulls, the owner sees which pulls to land or close to free it, in one look.

Done:

[ ] A hold for a hot file in src/crew/held.ts carries pulls: the numbers of the open pulls that touch that file, oldest first, at most 8. They are read from the per-pull files the picker already caches (rememberPullFiles in src/crew/hot_files.ts, with a small exported reader if needed). No new git call.
[ ] GET /api/v1/repos/:owner/:name/map returns them on held for each held issue. The detail sentence is unchanged.
[ ] The web Flow panel (src/web/pages/flow-panel.ts) lists them as links after the sentence (#7316 #7327 …), escaped as the rest of the panel is.
[ ] A test (e.g. test/held-hot-pulls.test.ts) remembers three pulls on one file, holds an issue that names it, and checks the numbers and their order in the map answer and the panel HTML.

Files: src/crew/held.ts, src/crew/hot_files.ts, src/web/pages/flow-panel.ts, a new test.

A hot-file hold names the open pulls on that file, oldest first, on the map and in the Flow panel #7423