perf(ui): enable KeepAlive on subscription list, tune prefetch, and reduce list/gesture animations

lib/widgets/staggered_list_animation.dart

@@ -1,5 +1,6 @@
 import 'package:flutter/material.dart';
 import 'dart:math' as math;
+import '../utils/reduce_motion.dart';
 
 /// 스태거 애니메이션이 적용된 리스트 위젯
 class StaggeredListAnimation extends StatefulWidget {
@@ -95,13 +96,14 @@ class _StaggeredListAnimationState extends State<StaggeredListAnimation>
 
   @override
   Widget build(BuildContext context) {
+    if (ReduceMotion.platform()) {
+      return widget.direction == Axis.vertical
+          ? Column(children: widget.children)
+          : Row(children: widget.children);
+    }
     return widget.direction == Axis.vertical
-        ? Column(
+        ? Column(children: _buildAnimatedChildren())
-            children: _buildAnimatedChildren(),
+        : Row(children: _buildAnimatedChildren());
-          )
-        : Row(
-            children: _buildAnimatedChildren(),
-          );
   }
 
   List<Widget> _buildAnimatedChildren() {
@@ -156,8 +158,9 @@ class _StaggeredAnimationItemState extends State<StaggeredAnimationItem>
   @override
   void initState() {
     super.initState();
+    final reduced = ReduceMotion.platform();
     _controller = AnimationController(
-      duration: widget.duration,
+      duration: reduced ? Duration.zero : widget.duration,
       vsync: this,
     );
 
@@ -170,7 +173,9 @@ class _StaggeredAnimationItemState extends State<StaggeredAnimationItem>
     ));
 
     _slideAnimation = Tween<Offset>(
-      begin: const Offset(0, 0.3),
+      begin: ReduceMotion.platform()
+          ? const Offset(0, 0.05)
+          : const Offset(0, 0.3),
       end: Offset.zero,
     ).animate(CurvedAnimation(
       parent: _controller,
@@ -185,11 +190,11 @@ class _StaggeredAnimationItemState extends State<StaggeredAnimationItem>
       curve: widget.curve,
     ));
 
-    // 지연 후 애니메이션 시작
+    // 지연 후 애니메이션 시작 (모션 축소 시 지연 없음)
-    Future.delayed(widget.delay * widget.index, () {
+    final startDelay =
-      if (mounted) {
+        ReduceMotion.platform() ? Duration.zero : widget.delay * widget.index;
-        _controller.forward();
+    Future.delayed(startDelay, () {
-      }
+      if (mounted) _controller.forward();
     });
   }
 
@@ -201,6 +206,7 @@ class _StaggeredAnimationItemState extends State<StaggeredAnimationItem>
 
   @override
   Widget build(BuildContext context) {
+    if (ReduceMotion.platform()) return widget.child;
     return AnimatedBuilder(
       animation: _controller,
       builder: (context, child) {

lib/widgets/subscription_list_widget.dart

@@ -71,6 +71,7 @@ class SubscriptionListWidget extends StatelessWidget {
                     physics: const NeverScrollableScrollPhysics(),
                     shrinkWrap: true,
                     padding: const EdgeInsets.symmetric(horizontal: 16),
+                    cacheExtent: 500,
                     prototypeItem: const SizedBox(height: 156),
                     itemCount: subscriptions.length,
                     itemBuilder: (context, subIndex) {
@@ -102,6 +103,7 @@ class SubscriptionListWidget extends StatelessWidget {
                             child: RepaintBoundary(
                               child: SwipeableSubscriptionCard(
                                 subscription: subscriptions[subIndex],
+                                keepAlive: true,
                                 onTap: () {
                                   Log.d(
                                       '[SubscriptionListWidget] SwipeableSubscriptionCard onTap 호출됨');

lib/widgets/swipeable_subscription_card.dart

@@ -2,12 +2,14 @@ import 'package:flutter/material.dart';
 import '../models/subscription_model.dart';
 import '../utils/haptic_feedback_helper.dart';
 import 'subscription_card.dart';
+import '../utils/reduce_motion.dart';
 
 class SwipeableSubscriptionCard extends StatefulWidget {
   final SubscriptionModel subscription;
   final VoidCallback? onEdit;
   final Future<void> Function()? onDelete;
   final VoidCallback? onTap;
+  final bool keepAlive;
 
   const SwipeableSubscriptionCard({
     super.key,
@@ -15,6 +17,7 @@ class SwipeableSubscriptionCard extends StatefulWidget {
     this.onEdit,
     this.onDelete,
     this.onTap,
+    this.keepAlive = false,
   });
 
   @override
@@ -23,7 +26,7 @@ class SwipeableSubscriptionCard extends StatefulWidget {
 }
 
 class _SwipeableSubscriptionCardState extends State<SwipeableSubscriptionCard>
-    with SingleTickerProviderStateMixin {
+    with SingleTickerProviderStateMixin, AutomaticKeepAliveClientMixin {
   // 상수 정의
   static const double _tapTolerance = 20.0; // 탭 허용 범위
   static const double _actionThresholdPercent = 0.15;
@@ -49,7 +52,9 @@ class _SwipeableSubscriptionCardState extends State<SwipeableSubscriptionCard>
   void initState() {
     super.initState();
     _controller = AnimationController(
-      duration: const Duration(milliseconds: 300),
+      duration: ReduceMotion.platform()
+          ? const Duration(milliseconds: 0)
+          : const Duration(milliseconds: 300),
       vsync: this,
     );
     _animation = Tween<double>(
@@ -215,10 +220,14 @@ class _SwipeableSubscriptionCardState extends State<SwipeableSubscriptionCard>
         right: isLeft ? 0 : 24,
       ),
       child: AnimatedOpacity(
-        duration: const Duration(milliseconds: 200),
+        duration: ReduceMotion.platform()
+            ? const Duration(milliseconds: 0)
+            : const Duration(milliseconds: 200),
         opacity: showIcon ? 1.0 : 0.0,
         child: AnimatedScale(
-          duration: const Duration(milliseconds: 200),
+          duration: ReduceMotion.platform()
+              ? const Duration(milliseconds: 0)
+              : const Duration(milliseconds: 200),
           scale: showIcon ? 1.0 : 0.5,
           child: Icon(
             isDeleteThreshold
@@ -236,9 +245,10 @@ class _SwipeableSubscriptionCardState extends State<SwipeableSubscriptionCard>
     return Transform.translate(
       offset: Offset(_currentOffset, 0),
       child: Transform.scale(
-        scale: 1.0 - (_currentOffset.abs() / 2000),
+        scale:
+            ReduceMotion.platform() ? 1.0 : 1.0 - (_currentOffset.abs() / 2000),
         child: Transform.rotate(
-          angle: _currentOffset / 2000,
+          angle: ReduceMotion.platform() ? 0.0 : _currentOffset / 2000,
           child: SubscriptionCard(
             subscription: widget.subscription,
             onTap: widget
@@ -251,6 +261,7 @@ class _SwipeableSubscriptionCardState extends State<SwipeableSubscriptionCard>
 
   @override
   Widget build(BuildContext context) {
+    super.build(context);
     // 웹과 모바일 모두 동일한 스와이프 기능 제공
     return Stack(
       children: [
@@ -266,4 +277,7 @@ class _SwipeableSubscriptionCardState extends State<SwipeableSubscriptionCard>
       ],
     );
   }
+
+  @override
+  bool get wantKeepAlive => widget.keepAlive;
 }