fix(gui): keep the parallel-active count outside the ellipsized hint

Both todo one-line surfaces truncate the active hint with overflow: hidden
and text-overflow: ellipsis. A "+N" appended to the first active task's name
therefore sat at the far end of the truncatable text, so a long task name or a
narrow viewport clipped exactly the part that reports the other running tasks,
leaving a parallel plan indistinguishable from a sequential one.

planSummary now returns activeContent and activeExtra as separate fields
instead of one joined activeHint, and each surface renders the count in its own
flex: none span beside the ellipsized name: .activeExtra in the collapsed plan
strip header, .extra in the todo_write row. Putting the count in front of the
name was rejected — the task name is what the reader looks for first.

The parallel-plan cases in todo-panel.spec.tsx now assert the count is a
separate element from the name, and both fail if the two are rejoined. The
assembled web snapshot re-records: the flex gap supplies the visual space, so
the transcript reads "实现 fixture 样本+1" with no space in the text nodes.

.agents/notes/implemented/feature/2026-07-26-todo-parallel-in-progress.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-07-26-todo-parallel-in-progress.md
-2026-07-26-todo-parallel-in-progress.md: eb8d78e2fe2895d952a355226ac518b9ccd40f98
-2026-07-26-todo-parallel-in-progress.zh.md: e610165f0170d92535a3709cc23dab8c77d2767f
+2026-07-26-todo-parallel-in-progress.md: 71123e07f6141346520114bff7029a4dca78ad0c
+2026-07-26-todo-parallel-in-progress.zh.md: 5355ea97247115ac0b2290b447d5ffab441e1a4d