feat: Phase 6 - Skeleton loaders for Groups/feed, seed groups SQL migration

sojorn_app/lib/screens/clusters/clusters_screen.dart

@@ -7,6 +7,7 @@ import '../../services/capsule_security_service.dart';
 import '../../theme/tokens.dart';
 import '../../theme/app_theme.dart';
 import 'group_screen.dart';
+import '../../widgets/skeleton_loader.dart';
 
 /// ClustersScreen — Discovery-first groups page.
 /// Shows "Your Groups" at top, then "Discover Communities" with category filtering.
@@ -156,7 +157,7 @@ class _ClustersScreenState extends ConsumerState<ClustersScreen>
 
   // ── Groups Tab (Your Groups + Discover) ──────────────────────────────
   Widget _buildGroupsTab() {
-    if (_isLoading) return const Center(child: CircularProgressIndicator());
+    if (_isLoading) return const SingleChildScrollView(child: SkeletonGroupList(count: 6));
     return RefreshIndicator(
       onRefresh: _loadAll,
       child: ListView(
@@ -220,10 +221,7 @@ class _ClustersScreenState extends ConsumerState<ClustersScreen>
 
           // Discover results
           if (_isDiscoverLoading)
-            const Padding(
-              padding: EdgeInsets.all(32),
-              child: Center(child: CircularProgressIndicator()),
-            )
+            const SkeletonGroupList(count: 4)
           else if (_discoverGroups.isEmpty)
             _EmptyDiscoverState(
               onCreateGroup: () => _showCreateSheet(context),
@@ -265,7 +263,7 @@ class _ClustersScreenState extends ConsumerState<ClustersScreen>
 
   // ── Capsules Tab ─────────────────────────────────────────────────────
   Widget _buildCapsuleTab() {
-    if (_isLoading) return const Center(child: CircularProgressIndicator());
+    if (_isLoading) return const SingleChildScrollView(child: SkeletonGroupList(count: 4));
     if (_myCapsules.isEmpty) return _EmptyState(
       icon: Icons.lock,
       title: 'No Capsules Yet',

sojorn_app/lib/widgets/skeleton_loader.dart

@@ -0,0 +1,191 @@
+import 'package:flutter/material.dart';
+import '../theme/app_theme.dart';
+
+/// Shimmer-animated skeleton placeholder for loading states.
+/// Use [SkeletonPostCard], [SkeletonGroupCard], etc. for specific shapes.
+class SkeletonBox extends StatefulWidget {
+  final double width;
+  final double height;
+  final double borderRadius;
+
+  const SkeletonBox({
+    super.key,
+    required this.width,
+    required this.height,
+    this.borderRadius = 8,
+  });
+
+  @override
+  State<SkeletonBox> createState() => _SkeletonBoxState();
+}
+
+class _SkeletonBoxState extends State<SkeletonBox>
+    with SingleTickerProviderStateMixin {
+  late AnimationController _controller;
+  late Animation<double> _animation;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = AnimationController(
+      vsync: this,
+      duration: const Duration(milliseconds: 1500),
+    )..repeat();
+    _animation = Tween<double>(begin: -1.0, end: 2.0).animate(
+      CurvedAnimation(parent: _controller, curve: Curves.easeInOutSine),
+    );
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AnimatedBuilder(
+      animation: _animation,
+      builder: (context, child) => Container(
+        width: widget.width,
+        height: widget.height,
+        decoration: BoxDecoration(
+          borderRadius: BorderRadius.circular(widget.borderRadius),
+          gradient: LinearGradient(
+            begin: Alignment(_animation.value - 1, 0),
+            end: Alignment(_animation.value, 0),
+            colors: [
+              AppTheme.navyBlue.withValues(alpha: 0.06),
+              AppTheme.navyBlue.withValues(alpha: 0.12),
+              AppTheme.navyBlue.withValues(alpha: 0.06),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+}
+
+/// Skeleton for a post card in the feed
+class SkeletonPostCard extends StatelessWidget {
+  const SkeletonPostCard({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      margin: const EdgeInsets.symmetric(horizontal: 14, vertical: 6),
+      padding: const EdgeInsets.all(16),
+      decoration: BoxDecoration(
+        color: AppTheme.cardSurface,
+        borderRadius: BorderRadius.circular(16),
+        border: Border.all(color: AppTheme.navyBlue.withValues(alpha: 0.06)),
+      ),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          // Author row
+          Row(
+            children: [
+              const SkeletonBox(width: 40, height: 40, borderRadius: 20),
+              const SizedBox(width: 10),
+              Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: const [
+                  SkeletonBox(width: 100, height: 12),
+                  SizedBox(height: 4),
+                  SkeletonBox(width: 60, height: 10),
+                ],
+              ),
+            ],
+          ),
+          const SizedBox(height: 14),
+          // Content lines
+          const SkeletonBox(width: double.infinity, height: 12),
+          const SizedBox(height: 6),
+          const SkeletonBox(width: double.infinity, height: 12),
+          const SizedBox(height: 6),
+          const SkeletonBox(width: 200, height: 12),
+          const SizedBox(height: 14),
+          // Action row
+          Row(
+            children: const [
+              SkeletonBox(width: 50, height: 10),
+              SizedBox(width: 20),
+              SkeletonBox(width: 50, height: 10),
+              SizedBox(width: 20),
+              SkeletonBox(width: 50, height: 10),
+            ],
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+/// Skeleton for a group discovery card
+class SkeletonGroupCard extends StatelessWidget {
+  const SkeletonGroupCard({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      margin: const EdgeInsets.only(bottom: 10),
+      padding: const EdgeInsets.all(14),
+      decoration: BoxDecoration(
+        color: AppTheme.cardSurface,
+        borderRadius: BorderRadius.circular(16),
+        border: Border.all(color: AppTheme.navyBlue.withValues(alpha: 0.06)),
+      ),
+      child: Row(
+        children: [
+          const SkeletonBox(width: 44, height: 44, borderRadius: 12),
+          const SizedBox(width: 12),
+          Expanded(
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              children: const [
+                SkeletonBox(width: 140, height: 13),
+                SizedBox(height: 4),
+                SkeletonBox(width: 200, height: 10),
+                SizedBox(height: 4),
+                SkeletonBox(width: 80, height: 10),
+              ],
+            ),
+          ),
+          const SkeletonBox(width: 56, height: 32, borderRadius: 20),
+        ],
+      ),
+    );
+  }
+}
+
+/// Skeleton list — shows N skeleton items
+class SkeletonFeedList extends StatelessWidget {
+  final int count;
+  const SkeletonFeedList({super.key, this.count = 4});
+
+  @override
+  Widget build(BuildContext context) {
+    return ListView.builder(
+      physics: const NeverScrollableScrollPhysics(),
+      shrinkWrap: true,
+      itemCount: count,
+      itemBuilder: (_, __) => const SkeletonPostCard(),
+    );
+  }
+}
+
+class SkeletonGroupList extends StatelessWidget {
+  final int count;
+  const SkeletonGroupList({super.key, this.count = 5});
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.symmetric(horizontal: 14),
+      child: Column(
+        children: List.generate(count, (_) => const SkeletonGroupCard()),
+      ),
+    );
+  }
+}