What
-----
- Fix the Ctrl+T transcript overlay so that very long exec output lines
are soft‑wrapped to the viewport width instead of being rendered as a
single truncated row.
- Add a regression test to `TranscriptOverlay` to ensure long exec
outputs are rendered on multiple lines in the overlay.
Why
----
- Previously, the transcript overlay rendered extremely long single exec
lines as one on‑screen row and simply cut them off at the right edge,
with no horizontal scrolling.
- This made it impossible to inspect the full content of long tool/exec
outputs in the transcript view, even though the main TUI view already
wrapped those lines.
- Fixes#7454.
How
----
- Update `ExecCell::transcript_lines` to wrap exec output lines using
the existing `RtOptions`/`word_wrap_line` helpers so that transcript
rendering is width‑aware.
- Reuse the existing line utilities to expand the wrapped `Line` values
into the transcript overlay, preserving styling while respecting the
current viewport width.
- Add `transcript_overlay_wraps_long_exec_output_lines` test in
`pager_overlay.rs` that constructs a long single‑line exec output,
renders the transcript overlay into a small buffer, and asserts that the
long marker string spans multiple rendered lines.