style: apply rustfmt across all crates and demos

Consistent formatting pass: line wrapping, import sorting, trailing
whitespace removal, let-chain indentation, merged derive attributes,
and unsafe block reformatting.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

crates/specialized/rtx-neuro-pinn/src/conductivity.rs

@@ -307,7 +307,10 @@ impl LayeredConductivity {
         let dz = point[2] - self.center[2];
         let r = (dx * dx + dy * dy + dz * dz).sqrt();
 
-        self.layers.iter().find(|&layer| layer.contains(r)).map(|v| v as _)
+        self.layers
+            .iter()
+            .find(|&layer| layer.contains(r))
+            .map(|v| v as _)
     }
 
     /// Get all layers