Reduce default grid sizes for sharded ocean climate to avoid OOM

Match the smaller defaults (64×64) used in PR #258 for the sharded
baroclinic instability test to avoid out-of-memory on CI runners.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: glwagner

sharding/sharded_ocean_climate_simulation_compile.jl

@@ -4,11 +4,11 @@ const args_settings = ArgParseSettings()
 @add_arg_table! args_settings begin
     "--grid-x"
         help = "Base factor for number of grid points on the x axis."
-        default = 192
+        default = 64
         arg_type = Int
     "--grid-y"
         help = "Base factor for number of grid points on the y axis."
-        default = 96
+        default = 64
         arg_type = Int
     "--grid-z"
         help = "Base factor for number of grid points on the z axis."

sharding/sharded_ocean_climate_simulation_run.jl

@@ -7,11 +7,11 @@ const args_settings = ArgParseSettings()
 @add_arg_table! args_settings begin
     "--grid-x"
         help = "Base factor for number of grid points on the x axis."
-        default = 192
+        default = 64
         arg_type = Int
     "--grid-y"
         help = "Base factor for number of grid points on the y axis."
-        default = 96
+        default = 64
         arg_type = Int
     "--grid-z"
         help = "Base factor for number of grid points on the z axis."