feat: implement Iteration 1 — AI recipe recommendations

Backend:
- Add Groq LLM client (llama-3.3-70b) for recipe generation with JSON
  retry strategy (retries only on parse errors, not API errors)
- Add Pexels client for parallel photo search per recipe
- Add saved_recipes table (migration 004) with JSONB fields
- Add GET /recommendations endpoint (profile-aware prompt building)
- Add POST/GET/GET{id}/DELETE /saved-recipes CRUD endpoints
- Wire gemini, pexels, recommendation, savedrecipe packages in main.go

Flutter:
- Add Recipe, SavedRecipe models with json_serializable
- Add RecipeService (getRecommendations, getSavedRecipes, save, delete)
- Add RecommendationsNotifier and SavedRecipesNotifier (Riverpod)
- Add RecommendationsScreen with skeleton loading and refresh FAB
- Add RecipeDetailScreen (SliverAppBar, nutrition tooltip, steps with timer)
- Add SavedRecipesScreen with Dismissible swipe-to-delete and empty state
- Update RecipesScreen to TabBar (Recommendations / Saved)
- Add /recipe-detail route outside ShellRoute (no bottom nav)
- Extend ApiClient with getList() and deleteVoid()

Project:
- Add CLAUDE.md with English-only rule for comments and commit messages

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

client/lib/features/recipes/widgets/skeleton_card.dart

@@ -0,0 +1,91 @@
+import 'package:flutter/material.dart';
+
+/// A pulsing placeholder card shown while recipes are loading from the AI.
+class SkeletonCard extends StatefulWidget {
+  const SkeletonCard({super.key});
+
+  @override
+  State<SkeletonCard> createState() => _SkeletonCardState();
+}
+
+class _SkeletonCardState extends State<SkeletonCard>
+    with SingleTickerProviderStateMixin {
+  late final AnimationController _ctrl;
+  late final Animation<double> _anim;
+
+  @override
+  void initState() {
+    super.initState();
+    _ctrl = AnimationController(
+      vsync: this,
+      duration: const Duration(milliseconds: 900),
+    )..repeat(reverse: true);
+    _anim = Tween<double>(begin: 0.25, end: 0.55).animate(
+      CurvedAnimation(parent: _ctrl, curve: Curves.easeInOut),
+    );
+  }
+
+  @override
+  void dispose() {
+    _ctrl.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return AnimatedBuilder(
+      animation: _anim,
+      builder: (context, _) {
+        final color = Colors.grey.withValues(alpha: _anim.value);
+        return Card(
+          clipBehavior: Clip.antiAlias,
+          child: Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Container(height: 180, color: color),
+              Padding(
+                padding: const EdgeInsets.all(12),
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    _Bar(width: 220, height: 18, color: color),
+                    const SizedBox(height: 8),
+                    _Bar(width: 160, height: 14, color: color),
+                    const SizedBox(height: 12),
+                    Row(
+                      children: [
+                        _Bar(width: 60, height: 12, color: color),
+                        const SizedBox(width: 12),
+                        _Bar(width: 60, height: 12, color: color),
+                        const SizedBox(width: 12),
+                        _Bar(width: 60, height: 12, color: color),
+                      ],
+                    ),
+                  ],
+                ),
+              ),
+            ],
+          ),
+        );
+      },
+    );
+  }
+}
+
+class _Bar extends StatelessWidget {
+  final double width;
+  final double height;
+  final Color color;
+
+  const _Bar({required this.width, required this.height, required this.color});
+
+  @override
+  Widget build(BuildContext context) => Container(
+        width: width,
+        height: height,
+        decoration: BoxDecoration(
+          color: color,
+          borderRadius: BorderRadius.circular(4),
+        ),
+      );
+}