style: Auto-fix format string warnings with clippy --fix

Applied clippy auto-fix for uninlined-format-args across:
- examples/
- benches/
- tests/

Reduced clippy warnings from 118 → 89.

Remaining warnings are mostly:
- Function length (pedantic, acceptable for examples/tests)
- unwrap_err in test error paths (acceptable)
- Minor style issues

All 742 tests still passing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: noahgift

tests/github_issue_8_elasticnet_safetensors_tests.rs

@@ -154,8 +154,7 @@ fn test_elasticnet_save_unfitted_model_fails() {
     let error_msg = result.unwrap_err();
     assert!(
         error_msg.contains("unfitted") || error_msg.contains("fit"),
-        "Error message should mention model is unfitted. Got: {}",
-        error_msg
+        "Error message should mention model is unfitted. Got: {error_msg}"
     );
 
     // Ensure no file was created
@@ -349,14 +348,12 @@ fn test_elasticnet_file_size_reasonable() {
     // - Total: < 2KB for this small model
     assert!(
         file_size < 2048,
-        "SafeTensors file should be compact. Got {} bytes",
-        file_size
+        "SafeTensors file should be compact. Got {file_size} bytes"
     );
 
     assert!(
         file_size > 28,
-        "SafeTensors file should contain data. Got {} bytes",
-        file_size
+        "SafeTensors file should contain data. Got {file_size} bytes"
     );
 
     // Cleanup
@@ -387,9 +384,7 @@ fn test_elasticnet_r2_score_preserved() {
     // R² scores should be identical
     assert!(
         (original_r2 - loaded_r2).abs() < 1e-6,
-        "R² score should be preserved: original={}, loaded={}",
-        original_r2,
-        loaded_r2
+        "R² score should be preserved: original={original_r2}, loaded={loaded_r2}"
     );
 
     // Cleanup
@@ -429,8 +424,7 @@ fn test_elasticnet_combined_regularization_behavior() {
     for i in 0..original_coef.len() {
         assert!(
             (original_coef[i] - loaded_coef[i]).abs() < 1e-6,
-            "Coefficient {} mismatch",
-            i
+            "Coefficient {i} mismatch"
         );
     }
 

tests/github_issue_8_forest_safetensors_tests.rs

@@ -117,26 +117,22 @@ fn test_forest_safetensors_metadata_includes_all_trees() {
 
     // Verify all 3 trees have required tensors
     for tree_idx in 0..3 {
-        let prefix = format!("tree_{}_", tree_idx);
+        let prefix = format!("tree_{tree_idx}_");
         assert!(
-            metadata.get(format!("{}node_features", prefix)).is_some(),
-            "Metadata must include tree {} node_features",
-            tree_idx
+            metadata.get(format!("{prefix}node_features")).is_some(),
+            "Metadata must include tree {tree_idx} node_features"
         );
         assert!(
-            metadata.get(format!("{}node_thresholds", prefix)).is_some(),
-            "Metadata must include tree {} node_thresholds",
-            tree_idx
+            metadata.get(format!("{prefix}node_thresholds")).is_some(),
+            "Metadata must include tree {tree_idx} node_thresholds"
         );
         assert!(
-            metadata.get(format!("{}node_classes", prefix)).is_some(),
-            "Metadata must include tree {} node_classes",
-            tree_idx
+            metadata.get(format!("{prefix}node_classes")).is_some(),
+            "Metadata must include tree {tree_idx} node_classes"
         );
         assert!(
-            metadata.get(format!("{}max_depth", prefix)).is_some(),
-            "Metadata must include tree {} max_depth",
-            tree_idx
+            metadata.get(format!("{prefix}max_depth")).is_some(),
+            "Metadata must include tree {tree_idx} max_depth"
         );
     }
 
@@ -159,8 +155,7 @@ fn test_forest_save_unfitted_model_fails() {
     let error_msg = result.unwrap_err();
     assert!(
         error_msg.contains("unfitted") || error_msg.contains("fit"),
-        "Error message should mention model is unfitted. Got: {}",
-        error_msg
+        "Error message should mention model is unfitted. Got: {error_msg}"
     );
 
     // Ensure no file was created
@@ -285,9 +280,7 @@ fn test_forest_accuracy_score_preserved() {
     // Accuracy should be identical
     assert!(
         (original_accuracy - loaded_accuracy).abs() < 1e-6,
-        "Accuracy should be preserved: original={}, loaded={}",
-        original_accuracy,
-        loaded_accuracy
+        "Accuracy should be preserved: original={original_accuracy}, loaded={loaded_accuracy}"
     );
 
     // Cleanup
@@ -348,10 +341,7 @@ fn test_forest_different_n_estimators() {
         .count();
     assert!(
         matches >= 3,
-        "10-tree forest predictions should mostly match: {:?} vs {:?} ({}/4 match)",
-        pred10_orig,
-        pred10_loaded,
-        matches
+        "10-tree forest predictions should mostly match: {pred10_orig:?} vs {pred10_loaded:?} ({matches}/4 match)"
     );
 
     // Cleanup
@@ -379,14 +369,12 @@ fn test_forest_file_size_reasonable() {
     // File should be reasonable (5 trees, each small)
     assert!(
         file_size < 20_000,
-        "SafeTensors file should be compact for small forest. Got {} bytes",
-        file_size
+        "SafeTensors file should be compact for small forest. Got {file_size} bytes"
     );
 
     assert!(
         file_size > 200,
-        "SafeTensors file should contain data. Got {} bytes",
-        file_size
+        "SafeTensors file should contain data. Got {file_size} bytes"
     );
 
     // Cleanup

tests/github_issue_8_lasso_safetensors_tests.rs

@@ -149,8 +149,7 @@ fn test_lasso_save_unfitted_model_fails() {
     let error_msg = result.unwrap_err();
     assert!(
         error_msg.contains("unfitted") || error_msg.contains("fit"),
-        "Error message should mention model is unfitted. Got: {}",
-        error_msg
+        "Error message should mention model is unfitted. Got: {error_msg}"
     );
 
     // Ensure no file was created
@@ -215,8 +214,7 @@ fn test_lasso_coefficients_and_hyperparams_preserved() {
     for i in 0..original_coef.len() {
         assert!(
             (original_coef[i] - loaded_coef[i]).abs() < 1e-6,
-            "Coefficient {} mismatch",
-            i
+            "Coefficient {i} mismatch"
         );
     }
 
@@ -416,14 +414,12 @@ fn test_lasso_file_size_reasonable() {
     // - Total: < 2KB for this small model
     assert!(
         file_size < 2048,
-        "SafeTensors file should be compact. Got {} bytes",
-        file_size
+        "SafeTensors file should be compact. Got {file_size} bytes"
     );
 
     assert!(
         file_size > 24,
-        "SafeTensors file should contain data. Got {} bytes",
-        file_size
+        "SafeTensors file should contain data. Got {file_size} bytes"
     );
 
     // Cleanup
@@ -454,9 +450,7 @@ fn test_lasso_r2_score_preserved() {
     // R² scores should be identical
     assert!(
         (original_r2 - loaded_r2).abs() < 1e-6,
-        "R² score should be preserved: original={}, loaded={}",
-        original_r2,
-        loaded_r2
+        "R² score should be preserved: original={original_r2}, loaded={loaded_r2}"
     );
 
     // Cleanup

tests/github_issue_8_ridge_safetensors_tests.rs

@@ -141,8 +141,7 @@ fn test_ridge_save_unfitted_model_fails() {
     let error_msg = result.unwrap_err();
     assert!(
         error_msg.contains("unfitted") || error_msg.contains("fit"),
-        "Error message should mention model is unfitted. Got: {}",
-        error_msg
+        "Error message should mention model is unfitted. Got: {error_msg}"
     );
 
     // Ensure no file was created
@@ -207,8 +206,7 @@ fn test_ridge_coefficients_preserved() {
     for i in 0..original_coef.len() {
         assert!(
             (original_coef[i] - loaded_coef[i]).abs() < 1e-6,
-            "Coefficient {} mismatch",
-            i
+            "Coefficient {i} mismatch"
         );
     }
 
@@ -352,14 +350,12 @@ fn test_ridge_file_size_reasonable() {
     // - Total: < 2KB for this small model
     assert!(
         file_size < 2048,
-        "SafeTensors file should be compact. Got {} bytes",
-        file_size
+        "SafeTensors file should be compact. Got {file_size} bytes"
     );
 
     assert!(
         file_size > 16,
-        "SafeTensors file should contain data. Got {} bytes",
-        file_size
+        "SafeTensors file should contain data. Got {file_size} bytes"
     );
 
     // Cleanup
@@ -390,9 +386,7 @@ fn test_ridge_r2_score_preserved() {
     // R² scores should be identical
     assert!(
         (original_r2 - loaded_r2).abs() < 1e-6,
-        "R² score should be preserved: original={}, loaded={}",
-        original_r2,
-        loaded_r2
+        "R² score should be preserved: original={original_r2}, loaded={loaded_r2}"
     );
 
     // Cleanup