rugnux live maps: one unit cell centred on the model; the viewer opens on all of it

/rugnux/map.ccp4 now serves one unit cell of map, centred on the model, instead of the model's box plus
5 A; along an axis where the model reaches further than the cell (a predicted model with long termini
in a small cell), the model plus 5 A instead, so that all of it has density. The Mol* viewer opens on
the whole cell and the model (map radius 0); a radius still draws the maps only around the centre of
view, Coot-style.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015CeEGgpKdfkCTJb3YNMJcu
(cherry picked from commit 1c1e1d96359f112d6820d972005e9f7eca4ebd50)

docs/python_client/docs/DefaultApi.md

@@ -4081,9 +4081,9 @@ This endpoint does not need any parameter.
 Get an electron-density map of the last rugnux live run
 
 The map of the placed model (`/rugnux/model.cif`) in CCP4 format (mode 2, float), made from the map
-coefficients written to `_maps.mtz`. It covers the box around the model plus 5 A on every side, sampled
-every d_min/3; the mean and RMS in its header are those of the whole unit cell, so contour levels in
-sigma are the usual ones.
+coefficients written to `_maps.mtz`. It covers one unit cell centred on the model - along an axis where
+the model reaches further than the cell, the model plus 5 A instead - sampled every d_min/3; the mean and
+RMS in its header are those of the unit cell, so contour levels in sigma are the usual ones.
 
 
 ### Example