Fix six things in the native heads

[SimonCropp]

Escape with the Linux context menu open reached the managed side as quit, which
closes the menu and then runs the command, so dismissing the menu closed the viewer

• and on Linux there is no tray to open it again from, so the queue went to staging.
  A click outside the menu reported nothing at all, leaving it floating until a row, a
  button or a key was hit, which is not what docs/viewer.md says of it. Both are
  dismissals now.

WindowShouldClose waits on events while the window is minimised, and it is called
inside deview_present, so minimising the Linux viewer stopped the managed loop being
pumped: a snapshot arriving after that was accepted by the listener and never shown.
FLAG_WINDOW_ALWAYS_RUN keeps the loop running, and a focus restores a minimised
window rather than leaving it in the taskbar.

The ImGui backend did not declare RendererHasVtxOffset and the renderer ignored the
vertex offset, so a draw list past 65535 vertices - a maximised 4K window of dense
long lines reaches that - wrapped its sixteen bit indices and drew scrambled panes,
with IM_ASSERT compiled out of the release build to say nothing about it.

A failed queue row on Linux was coloured and left unmarked, while the other three
heads and the docs show " !" after the label.

Trackpad scrolling: the Linux head truncated fractional wheel offsets to zero, and
the Mac head rounded points to notches - so an ordinary flick, which is tens of
points, arrived as tens of notches and the managed side multiplied it by three,
while slow movement rounded away to nothing. Both accumulate now, and macOS converts
points and lines separately.

macOS tooltips: refreshToolTips removed and re-added every tracking rectangle on
every frame, and AppKit times its tooltip delay from the moment the cursor enters
one, so the delay was restarted before it could elapse and queue tooltips never
appeared. The rectangles are rebuilt only when they change.

The macOS head derived "Pending (N)" from the queue it was handed, which is the visible slice - sized to the body, with folded group members left out - so thirty pending in a sixteen row body read "Pending (16)" beside "inline 1 of 30". DeviewScreen carries the real count now, which takes DEVIEW_VERSION to 7.

The binaries these compile into are committed, so the build-native workflow's rebuild has to land on this branch before it is merged. It runs on every push here and opens its PR against this branch.