refactor(records): use CategoryKind for column filtering, stabilize _Measure position

- Filter records-mode columns by CategoryKind instead of string names
- Simplify cell fetching: matching_cells already handles empty filters
- Sort _Measure to always appear right before Value column

Made-with: Cursor

src/view/layout.rs

@@ -1,6 +1,7 @@
 use std::rc::Rc;
 
 use crate::model::Model;
+use crate::model::category::CategoryKind;
 use crate::model::cell::{CellKey, CellValue};
 use crate::view::{Axis, View};
 
@@ -132,22 +133,12 @@ impl GridLayout {
         page_coords: Vec<(String, String)>,
         none_cats: Vec<String>,
     ) -> Self {
-        // Filter cells by page_coords
-        let partial: Vec<(String, String)> = page_coords.clone();
-        let mut records: Vec<(CellKey, CellValue)> = if partial.is_empty() {
-            model
-                .data
-                .iter_cells()
-                .map(|(k, v)| (k, v.clone()))
-                .collect()
-        } else {
-            model
-                .data
-                .matching_cells(&partial)
-                .into_iter()
-                .map(|(k, v)| (k, v.clone()))
-                .collect()
-        };
+        let mut records: Vec<(CellKey, CellValue)> = model
+            .data
+            .matching_cells(&page_coords)
+            .into_iter()
+            .map(|(k, v)| (k, v.clone()))
+            .collect();
         // Sort for deterministic ordering
         records.sort_by(|a, b| a.0.0.cmp(&b.0.0));
 
@@ -157,12 +148,22 @@ impl GridLayout {
             .collect();
 
         // Synthesize col items: one per non-virtual category + "Value"
-        let cat_names: Vec<String> = model
+        let mut cat_names: Vec<String> = model
             .category_names()
             .into_iter()
-            .filter(|c| *c != "_Index" && *c != "_Dim")
+            .filter(|c| {
+                let kind = model.category(c).map(|cat| cat.kind);
+                !matches!(kind, Some(CategoryKind::VirtualIndex | CategoryKind::VirtualDim))
+            })
             .map(String::from)
             .collect();
+        // _Measure goes last among category columns (right before Value)
+        cat_names.sort_by_key(|c| {
+            matches!(
+                model.category(c).map(|cat| cat.kind),
+                Some(CategoryKind::VirtualMeasure)
+            )
+        });
         let mut col_items: Vec<AxisEntry> = cat_names
             .iter()
             .map(|c| AxisEntry::DataItem(vec![c.clone()]))