fix(ai-term): stop F9 toggle shrinking the agent window each cycle

The F9 toggle captured the agent window's body-height and replayed it as
body-lines. Body-height subtracts the mode line's pixel height, which differs
between an active and an inactive mode line; the agent is captured active but
redisplayed inactive, so under a theme whose mode-line-inactive is shorter than
a text line the window lost ~1 line per toggle.

Capture and replay total-height for the vertical axis instead, via the renamed
cj/window-replay-size. Total-height is identical active or inactive and has no
mode-line-pixel dependence, so the round-trip is a fixed point. Width keeps
body-width (total-width has the position-dependent divider problem that total-
height does not). The shared lib fix covers the F12 terminal toggle too.

The shrink only manifests in a GUI frame, so it is not reproducible in the
batch harness; the unit tests pin the new total-height contract.

1 files changed, 3 insertions, 2 deletions

diff --git a/modules/term-config.el b/modules/term-config.el
index 33f54d75a..0a7991409 100644
--- a/modules/term-config.el
+++ b/modules/term-config.el
@@ -313,8 +313,9 @@ Symbol: right, left, or below.  `above' is never stored.  nil means use the
 default `below' for F12's traditional bottom split.")
 
 (defvar cj/--term-toggle-last-size nil
-  "Last user-chosen body size for the F12 terminal display.
-Positive integer: body-cols (right/left) or body-lines (below/above).
+  "Last user-chosen size for the F12 terminal display.
+Positive integer: body-cols (right/left) or total-lines (below/above) -- see
+`cj/window-replay-size' for why the vertical axis uses total, not body.
 nil means fall back to `cj/term-toggle-window-height' as a fraction.")
 
 (defun cj/--term-toggle-buffer-p (buffer)