fix: prevent unnecessary animation on Tab component mount

Fixes a bug where the Tab animation would run on initial mount even when
already at the target state. This caused unnecessary animation work and
potential visual glitches.

Changes:
- Added isInitialMount ref to track first render
- Skip animation on mount, immediately set value instead
- Subsequent changes animate normally

This ensures underlines appear instantly on first render and only animate
when the active state actually changes.

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

Co-Authored-By: Claude <[email protected]>

Author: georgewrmarshall

app/component-library/components-temp/Tabs/Tab/Tab.tsx

@@ -24,8 +24,17 @@ const Tab: React.FC<TabProps> = ({
 }) => {
   const tw = useTailwind();
   const scaleAnim = useRef(new Animated.Value(isActive ? 1 : 0)).current;
+  const isInitialMount = useRef(true);
 
   useEffect(() => {
+    // Skip animation on initial mount - just set the value
+    if (isInitialMount.current) {
+      isInitialMount.current = false;
+      scaleAnim.setValue(isActive && !isDisabled ? 1 : 0);
+      return;
+    }
+
+    // Animate on subsequent changes
     Animated.timing(scaleAnim, {
       toValue: isActive && !isDisabled ? 1 : 0,
       duration: AnimationDuration.Fast,