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>

backend/internal/savedrecipe/model.go

@@ -0,0 +1,43 @@
+package savedrecipe
+
+import (
+	"encoding/json"
+	"time"
+)
+
+// SavedRecipe is a recipe saved by a specific user.
+type SavedRecipe struct {
+	ID          string          `json:"id"`
+	UserID      string          `json:"-"`
+	Title       string          `json:"title"`
+	Description *string         `json:"description"`
+	Cuisine     *string         `json:"cuisine"`
+	Difficulty  *string         `json:"difficulty"`
+	PrepTimeMin *int            `json:"prep_time_min"`
+	CookTimeMin *int            `json:"cook_time_min"`
+	Servings    *int            `json:"servings"`
+	ImageURL    *string         `json:"image_url"`
+	Ingredients json.RawMessage `json:"ingredients"`
+	Steps       json.RawMessage `json:"steps"`
+	Tags        json.RawMessage `json:"tags"`
+	Nutrition   json.RawMessage `json:"nutrition_per_serving"`
+	Source      string          `json:"source"`
+	SavedAt     time.Time       `json:"saved_at"`
+}
+
+// SaveRequest is the body for POST /saved-recipes.
+type SaveRequest struct {
+	Title       string          `json:"title"`
+	Description string          `json:"description"`
+	Cuisine     string          `json:"cuisine"`
+	Difficulty  string          `json:"difficulty"`
+	PrepTimeMin int             `json:"prep_time_min"`
+	CookTimeMin int             `json:"cook_time_min"`
+	Servings    int             `json:"servings"`
+	ImageURL    string          `json:"image_url"`
+	Ingredients json.RawMessage `json:"ingredients"`
+	Steps       json.RawMessage `json:"steps"`
+	Tags        json.RawMessage `json:"tags"`
+	Nutrition   json.RawMessage `json:"nutrition_per_serving"`
+	Source      string          `json:"source"`
+}