Carry the ZDC box shapes in double

This converts the boxpar array of the ZDC geometry from float to
double.

- The rest of the module was already double: the Geometry.h constants
  and the tubpar, tubspar and conpar arrays.
- boxpar was mixed into double placements, as in
  Gspos(Q12T, ..., tubspar[1] + boxpar[0], ...), so a double seat was
  computed from a float half-length.
- The near-coincident face pairs in the geometry fall from 687 in 80
  mothers to 683 in 79.

The effect on ZDC hits is not measured: a box gun at central rapidity
produces no ZDC hits at all, so this needs a generator that populates
the beam line.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
(cherry picked from commit 62df60a2874d17d9e8b71a080f809ab863e224b3)

Author: sawenzel

Detectors/ZDC/simulation/src/Detector.cxx

@@ -749,7 +749,7 @@ void Detector::createAsideBeamLine()
 {
 
   double tubpar[3] = {0., 0., 0};
-  float boxpar[3] = {0., 0., 0};
+  double boxpar[3] = {0., 0., 0};
   double tubspar[5] = {0., 0., 0., 0., 0.};
   double conpar[15] = {0.}; // all elements will be 0
 
@@ -1401,7 +1401,7 @@ void Detector::createAsideBeamLine()
 void Detector::createCsideBeamLine()
 {
   double tubpar[3] = {0., 0., 0};
-  float boxpar[3] = {0., 0., 0};
+  double boxpar[3] = {0., 0., 0};
   double tubspar[5] = {0., 0., 0., 0., 0.};
   double conpar[15] = {
     0.,