Fix loc_violations used uninitialized in MPI_Allreduce

loc_violations is never set to 0 before the conditional that may or
may not assign it. Non-violating ranks sum garbage in the reduction.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

src/pre_process/m_data_output.fpp

@@ -476,7 +476,7 @@ contains
 
         ! Generic loop iterators
         integer :: i, j, k, l
-        real(wp) :: loc_violations, glb_violations
+        real(wp) :: loc_violations = 0._wp, glb_violations
 
         ! Downsample variables
         integer :: m_ds, n_ds, p_ds