feat: Engine diagnostics (#92)

Adds a `Diagnostics` component that shows the following diagnostics from the last realization:

- Confirmation of success or a short description of what failed.
- The value of the loss function at each step.
- The spectrum of the Hessian at each step.

The loss and spectrum plots are shown on switchable panels.

Also includes some refactoring/renaming of existing code.

Co-authored-by: Aaron Fenyes <aaron.fenyes@fareycircles.ooo>
Reviewed-on: StudioInfinity/dyna3#92
Co-authored-by: Vectornaut <vectornaut@nobody@nowhere.net>
Co-committed-by: Vectornaut <vectornaut@nobody@nowhere.net>

app-proto/examples/common/print.rs

@@ -0,0 +1,36 @@
+#![allow(dead_code)]
+
+use nalgebra::DMatrix;
+
+use dyna3::engine::{Q, DescentHistory, Realization};
+
+pub fn title(title: &str) {
+    println!("─── {title} ───");
+}
+
+pub fn realization_diagnostics(realization: &Realization) {
+    let Realization { result, history } = realization;
+    println!();
+    if let Err(ref message) = result {
+        println!("❌️ {message}");
+    } else {
+        println!("✅️ Target accuracy achieved!");
+    }
+    println!("Steps: {}", history.scaled_loss.len() - 1);
+    println!("Loss: {}", history.scaled_loss.last().unwrap());
+}
+
+pub fn gram_matrix(config: &DMatrix<f64>) {
+    println!("\nCompleted Gram matrix:{}", (config.tr_mul(&*Q) * config).to_string().trim_end());
+}
+
+pub fn config(config: &DMatrix<f64>) {
+    println!("\nConfiguration:{}", config.to_string().trim_end());
+}
+
+pub fn loss_history(history: &DescentHistory) {
+    println!("\nStep │ Loss\n─────┼────────────────────────────────");
+    for (step, scaled_loss) in history.scaled_loss.iter().enumerate() {
+        println!("{:<4} │ {}", step, scaled_loss);
+    }
+}