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/training/rtx-transformers/src/optimizers/matrix_utils.rs

@@ -473,8 +473,7 @@ pub fn kronecker_product(a: &Tensor, b: &Tensor) -> Result<Tensor> {
         }
     }
 
-    Tensor::from_data(result, [result_rows, result_cols], device)
-        .map_err(TransformerError::from)
+    Tensor::from_data(result, [result_rows, result_cols], device).map_err(TransformerError::from)
 }
 
 /// Add diagonal regularization: A + ε*I
@@ -573,7 +572,7 @@ impl StatisticsAccumulator {
     }
 
     /// Get current covariance estimate
-    #[must_use] 
+    #[must_use]
     pub fn get_covariance(&self) -> &Tensor {
         &self.covariance
     }