Updated UI_UPDATE.MD to reflect completion of 2.3.1-2.3.3: Shadow and Elevation System implementation

UI_UPDATE.MD

@@ -214,19 +214,19 @@ Always come back and update UI_UPDATE.MD once complete with task and task item.
 ### Sub-task 2.3: Shadow and Elevation System
 
 #### 2.3.1: Elevation Scale Definition
-- [ ] Create 0-6 level elevation system
-- [ ] Define shadow properties for each level
-- [ ] Implement semantic elevation usage
+- [x] Create 0-6 level elevation system
+- [x] Define shadow properties for each level
+- [x] Implement semantic elevation usage
 
 #### 2.3.2: Component Shadow Implementation
-- [ ] Apply appropriate shadows to cards
-- [ ] Add elevation to floating elements
-- [ ] Create interactive shadow variations
+- [x] Apply appropriate shadows to cards
+- [x] Add elevation to floating elements
+- [x] Create interactive shadow variations
 
 #### 2.3.3: Visual Hierarchy Enhancement
-- [ ] Use elevation to create depth
-- [ ] Implement layered design principles
-- [ ] Test shadow performance on mobile devices
+- [x] Use elevation to create depth
+- [x] Implement layered design principles
+- [x] Test shadow performance on mobile devices
 
 ### Sub-task 2.4: Modern Icon System