Add tender card shimmer loading

lib/views/tenders/widgets/recommended_tenders_view.dart

@@ -6,6 +6,7 @@ import 'package:tm_app/view_models/ai_recommendations_view_model.dart';
 
 import '../strings/tenders_strings.dart';
 import 'main_tenders_slider.dart';
+import 'tender_card_shimmer.dart';
 
 /// The "Recommended" tab body. Handles loading, empty/"still learning",
 /// error+retry and the recommended tender list for [AiRecommendationsViewModel].
@@ -34,7 +35,7 @@ class _RecommendedTendersViewState extends State<RecommendedTendersView> {
     return Consumer<AiRecommendationsViewModel>(
       builder: (context, vm, child) {
         if (vm.isLoading) {
-          return const _LoadingSkeleton();
+          return _LoadingSkeleton(isDesktop: widget.isDesktop);
         }
         if (vm.errorMessage != null) {
           return _MessageState(
@@ -152,23 +153,18 @@ class _MessageState extends StatelessWidget {
 
 /// Simple placeholder list shown while recommendations load.
 class _LoadingSkeleton extends StatelessWidget {
-  const _LoadingSkeleton();
+  const _LoadingSkeleton({required this.isDesktop});
+
+  final bool isDesktop;
 
   @override
   Widget build(BuildContext context) {
     return ListView.separated(
       padding: EdgeInsets.all(16.0.h()),
-      itemCount: 4,
-      separatorBuilder: (_, __) => SizedBox(height: 12.0.h()),
-      itemBuilder:
-          (context, index) => Container(
-            height: 120.0.h(),
-            decoration: BoxDecoration(
-              color: AppColors.grey0,
-              borderRadius: BorderRadius.circular(12.0.w()),
-              border: Border.all(color: AppColors.grey30),
-            ),
-          ),
+      itemCount: isDesktop ? 3 : 2,
+      separatorBuilder:
+          (_, __) => SizedBox(height: isDesktop ? 20.0.h() : 52.0.h()),
+      itemBuilder: (context, index) => TenderCardShimmer(isDesktop: isDesktop),
     );
   }
 }

lib/views/tenders/widgets/tender_card_shimmer.dart

@@ -0,0 +1,173 @@
+import 'package:flutter/material.dart';
+import 'package:tm_app/core/theme/colors.dart';
+import 'package:tm_app/core/utils/size_config.dart';
+
+class TenderCardShimmer extends StatelessWidget {
+  const TenderCardShimmer({super.key, this.isDesktop = false});
+
+  final bool isDesktop;
+
+  @override
+  Widget build(BuildContext context) {
+    return _Shimmer(
+      child: Container(
+        width: double.infinity,
+        margin: EdgeInsets.symmetric(horizontal: 16.0.w()),
+        height: isDesktop ? 350.0.h() : 587.0.h(),
+        padding: EdgeInsets.all(16.0.w()),
+        decoration: BoxDecoration(
+          color: AppColors.grey0,
+          borderRadius: BorderRadius.circular(12),
+          border: Border.all(color: AppColors.grey30),
+        ),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            _bar(width: isDesktop ? 120.0.w() : 140.0.w(), height: 14.0.h()),
+            SizedBox(height: 16.0.h()),
+            _block(height: isDesktop ? 58.0.h() : 70.0.h()),
+            SizedBox(height: isDesktop ? 12.0.h() : 20.0.h()),
+            _bar(width: double.infinity, height: 18.0.h()),
+            SizedBox(height: 8.0.h()),
+            _fractionBar(widthFactor: 0.72, height: 18.0.h()),
+            SizedBox(height: 16.0.h()),
+            _bar(width: double.infinity, height: 14.0.h()),
+            SizedBox(height: 8.0.h()),
+            _bar(width: double.infinity, height: 14.0.h()),
+            SizedBox(height: 8.0.h()),
+            _fractionBar(widthFactor: 0.55, height: 14.0.h()),
+            const Spacer(),
+            Row(
+              children: [
+                _circle(size: 24.0.h()),
+                SizedBox(width: 8.0.w()),
+                _bar(width: 60.0.w(), height: 14.0.h()),
+                const Spacer(),
+                _pill(width: 108.0.w(), height: 40.0.h()),
+              ],
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _bar({required double width, required double height}) {
+    return Container(
+      width: width,
+      height: height,
+      decoration: BoxDecoration(
+        color: AppColors.grey20,
+        borderRadius: BorderRadius.circular(6),
+      ),
+    );
+  }
+
+  Widget _fractionBar({required double widthFactor, required double height}) {
+    return FractionallySizedBox(
+      widthFactor: widthFactor,
+      alignment: AlignmentDirectional.centerStart,
+      child: _bar(width: double.infinity, height: height),
+    );
+  }
+
+  Widget _block({required double height}) {
+    return Container(
+      width: double.infinity,
+      height: height,
+      decoration: BoxDecoration(
+        color: AppColors.grey20,
+        borderRadius: BorderRadius.circular(4),
+      ),
+    );
+  }
+
+  Widget _pill({required double width, required double height}) {
+    return Container(
+      width: width,
+      height: height,
+      decoration: BoxDecoration(
+        color: AppColors.grey20,
+        borderRadius: BorderRadius.circular(100),
+      ),
+    );
+  }
+
+  Widget _circle({required double size}) {
+    return Container(
+      width: size,
+      height: size,
+      decoration: BoxDecoration(
+        color: AppColors.grey20,
+        shape: BoxShape.circle,
+      ),
+    );
+  }
+}
+
+class _Shimmer extends StatefulWidget {
+  const _Shimmer({required this.child});
+
+  final Widget child;
+
+  @override
+  State<_Shimmer> createState() => _ShimmerState();
+}
+
+class _ShimmerState extends State<_Shimmer>
+    with SingleTickerProviderStateMixin {
+  late final AnimationController _controller;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(
+      vsync: this,
+      duration: const Duration(milliseconds: 1400),
+    )..repeat();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AnimatedBuilder(
+      animation: _controller,
+      child: widget.child,
+      builder: (context, child) {
+        return ShaderMask(
+          blendMode: BlendMode.srcATop,
+          shaderCallback: (bounds) {
+            final shimmerWidth = bounds.width * 0.8;
+            final offset = (bounds.width + shimmerWidth) * _controller.value;
+            return LinearGradient(
+              begin: Alignment.centerLeft,
+              end: Alignment.centerRight,
+              colors: [AppColors.grey20, AppColors.grey10, AppColors.grey20],
+              stops: const [0.25, 0.5, 0.75],
+              transform: _SlidingGradientTransform(
+                slidePercent: (offset - shimmerWidth) / bounds.width,
+              ),
+            ).createShader(bounds);
+          },
+          child: child,
+        );
+      },
+    );
+  }
+}
+
+class _SlidingGradientTransform extends GradientTransform {
+  const _SlidingGradientTransform({required this.slidePercent});
+
+  final double slidePercent;
+
+  @override
+  Matrix4 transform(Rect bounds, {TextDirection? textDirection}) {
+    return Matrix4.translationValues(bounds.width * slidePercent, 0, 0);
+  }
+}