test(import): add tests for label field import behavior

Add two new tests for label field functionality:
- label_fields_imported_as_label_category_coords: Verifies that
  high-cardinality fields (>20 distinct values) are classified as
  Label kind, default to accepted, and are stored as category coords
- label_category_defaults_to_none_axis: Verifies that label categories
  default to Axis::None in the active view

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/Qwen3.5-35B-A3B-GGUF:Q5_K_M)

src/import/wizard.rs

@@ -631,6 +631,46 @@ mod tests {
         assert!(model.category("Measure").is_some());
     }
 
+    #[test]
+    fn label_fields_imported_as_label_category_coords() {
+        use crate::model::category::CategoryKind;
+        // 25 unique descriptions → classified as Label (> CATEGORY_THRESHOLD=20)
+        let records: Vec<serde_json::Value> = (0..25)
+            .map(|i| json!({"region": "East", "desc": format!("row-{i}"), "revenue": i as f64}))
+            .collect();
+        let raw = serde_json::Value::Array(records);
+        let p = ImportPipeline::new(raw);
+        let desc = p.proposals.iter().find(|p| p.field == "desc").unwrap();
+        assert_eq!(desc.kind, FieldKind::Label);
+        assert!(desc.accepted, "labels should default to accepted");
+
+        let model = p.build_model().unwrap();
+        // Label field exists as a category with Label kind
+        let cat = model.category("desc").expect("desc category exists");
+        assert_eq!(cat.kind, CategoryKind::Label);
+        // Each record's cell key carries the desc label coord
+        use crate::model::cell::CellKey;
+        let k = CellKey::new(vec![
+            ("Measure".to_string(), "revenue".to_string()),
+            ("desc".to_string(), "row-7".to_string()),
+            ("region".to_string(), "East".to_string()),
+        ]);
+        assert_eq!(model.get_cell(&k).and_then(|v| v.as_f64()), Some(7.0));
+    }
+
+    #[test]
+    fn label_category_defaults_to_none_axis() {
+        use crate::view::Axis;
+        let records: Vec<serde_json::Value> = (0..25)
+            .map(|i| json!({"region": "East", "desc": format!("r{i}"), "n": 1.0}))
+            .collect();
+        let raw = serde_json::Value::Array(records);
+        let p = ImportPipeline::new(raw);
+        let model = p.build_model().unwrap();
+        let v = model.active_view();
+        assert_eq!(v.axis_of("desc"), Axis::None);
+    }
+
     #[test]
     fn build_model_cells_match_source_data() {
         let raw = json!([