rename Stimulus -> RegionGated

crates/applications/wavefront/src/main.rs

@@ -11,7 +11,7 @@ use coremem::{mat, Driver};
 use coremem::geom::{Coord as _, Cube, Index};
 use coremem::units::Seconds;
 use coremem::sim::spirv::{self, SpirvSim};
-use coremem::stim::{Stimulus, TimeVarying as _, UniformStimulus};
+use coremem::stim::{RegionGated, TimeVarying as _, UniformStimulus};
 use coremem::cross::vec::Vec3;
 
 type Mat = mat::FullyGenericMaterial<f32>;
@@ -46,7 +46,7 @@ fn main() {
         Index::new(201, height*3/4, 1).to_meters(feature_size),
     );
     // emit a constant E/H delta over this region for 100 femtoseconds
-    let stim = Stimulus::new(
+    let stim = RegionGated::new(
         center_region,
         UniformStimulus::new(
             Vec3::new(2e19, 0.0, 0.0),  // E field (per second)