T24c round 1 fix

- FileChangeCard's header wraps: the path keeps label_width, counts and
  verdict drop below as one group; MultiFileDiffReview's header wraps its
  counts and its all-buttons inside the box, parted by justify_between
- git::DiffViewer's fold rows are Tab stops with a focus ring when the
  owner opens folds; every row keeps a transparent border so heights match;
  an inert fold no longer shows a pointer
- tests: a_narrow_review_wraps_its_rows_inside_its_box,
  git::a_fold_opens_from_the_keyboard; the gallery adds a 280px review
- AGENTS: taffy drops gaps beside an auto margin; wrapping headers

AGENTS.md

@@ -134,6 +134,8 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - The system time zone comes from `typography::format::system_zone`, which fails loud; jiff's `TimeZone::system()` falls back to UTC in silence.
 - A list opens with its cursor on the current choice: Select on the chosen row, Combobox on its value, MultiSelect on the first one ticked.
 - A search step, a tool call or an agent's step says where it stands with `chat::StepState` and draws it with `chat::step_mark`.
+- A flex line whose free space goes to an auto margin loses its gaps in taffy 0.9. A row that parts left and right groups its sides and uses `justify_between`; `ml_auto` is safe only beside a `flex_1` item that leaves no free space.
+- A header that holds a name beside counts and actions wraps: `flex_wrap`, the name `flex_1` with `min_w(label_width)`, the rest one `flex_none` group that drops below.
 
 ## Decisions