Improve JS enum_val() with caching and single-value lookup

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

docs/CLAUDE.dist.md

@@ -937,8 +937,8 @@ Integer-backed enums with model-level mapping to constants, labels, and custom p
 class Project_Model extends Rsx_Model_Abstract {
     public static $enums = [
         'status_id' => [
-            1 => ['constant' => 'STATUS_ACTIVE', 'label' => 'Active', 'badge' => 'bg-success'],
-            2 => ['constant' => 'STATUS_ARCHIVED', 'label' => 'Archived', 'selectable' => false],
+            1 => ['constant' => 'STATUS_ACTIVE', 'label' => 'Active', 'badge' => 'bg-success', 'order' => 1],
+            2 => ['constant' => 'STATUS_ARCHIVED', 'label' => 'Archived', 'selectable' => false, 'order' => 99],
         ],
     ];
 }
@@ -949,6 +949,10 @@ echo $project->status_label;  // "Active"
 echo $project->status_badge;  // "bg-success" (custom property)
 ```
 
+**Special properties**:
+- `order` - Sort position in dropdowns (default: 0, lower first)
+- `selectable` - Include in dropdown options (default: true). Non-selectable items excluded from `field_enum_select()` but still shown if current value.
+
 **Migration:** Use BIGINT for enum columns, TINYINT(1) for booleans. Run `rsx:migrate:document_models` after adding enums.
 
 ### Model Fetch