feat: measure distortion

Cherry-picked from commit 0de32f5, on the branch Vectornaut:near_miss.

app-proto/src/components/diagnostics.rs

@@ -111,6 +111,28 @@ fn StepInput() -> View {
     }
 }
 
+#[component]
+fn DistortionGauge() -> View {
+    let state = use_context::<AppState>();
+    let total_distortion = create_memo(move || {
+        state.assembly.regulators.with(|regs| {
+            let mut total = 0.0;
+            for reg in regs {
+                if let Some(distortion) = reg.distortion() {
+                    total += distortion.get();
+                }
+            }
+            total
+        })
+    });
+    
+    view! {
+        div(id = "distortion-gauge") {
+            "Distortion: " (total_distortion.with(|distort| distort.to_string()))
+        }
+    }
+}
+
 fn into_log10_time_point((step, value): (usize, f64)) -> Vec<Option<f64>> {
     vec![
         Some(step as f64),
@@ -315,6 +337,7 @@ pub fn Diagnostics() -> View {
             }
             DiagnosticsPanel(name = "loss") { LossHistory {} }
             DiagnosticsPanel(name = "spectrum") { SpectrumHistory {} }
+            DistortionGauge {}
         }
     }
 }